diff --git a/app/debug/app-debug.apk b/app/debug/app-debug.apk
deleted file mode 100644
index f60bc27..0000000
Binary files a/app/debug/app-debug.apk and /dev/null differ
diff --git a/app/debug/output-metadata.json b/app/debug/output-metadata.json
deleted file mode 100644
index e7ddcb5..0000000
--- a/app/debug/output-metadata.json
+++ /dev/null
@@ -1,20 +0,0 @@
-{
-  "version": 3,
-  "artifactType": {
-    "type": "APK",
-    "kind": "Directory"
-  },
-  "applicationId": "meow.sweetbread.lincalc",
-  "variantName": "debug",
-  "elements": [
-    {
-      "type": "SINGLE",
-      "filters": [],
-      "attributes": [],
-      "versionCode": 1,
-      "versionName": "1.0",
-      "outputFile": "app-debug.apk"
-    }
-  ],
-  "elementType": "File"
-}
\ No newline at end of file
diff --git a/app/src/main/java/meow/sweetbread/lincalc/MainActivity.kt b/app/src/main/java/meow/sweetbread/lincalc/MainActivity.kt
index 7ad578a..f7ff23e 100644
--- a/app/src/main/java/meow/sweetbread/lincalc/MainActivity.kt
+++ b/app/src/main/java/meow/sweetbread/lincalc/MainActivity.kt
@@ -5,117 +5,382 @@ import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
 import android.util.Log
 import android.widget.Button
+import android.widget.ImageButton
 import android.widget.TextView
+import kotlin.math.pow
+import kotlin.math.sqrt
 
 class MainActivity : AppCompatActivity() {
-    private var tmp_buf = ""
-    var buffer = listOf<String>()
-    private var act_ena = false
-    var priority = HashMap<String, Int>()
+    private var priority = HashMap<String, Int>()
+    private var tokensType = HashMap<String, Tokens>()
+    private val leftAssociative = arrayOf("^")
+    private var constants = HashMap<String, Double>()
 
     @SuppressLint("MissingInflatedId", "CutPasteId")
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
 
-        priority.put("+", 1)
-        priority.put("-", 1)
-        priority.put("*", 2)
-        priority.put("/", 2)
+        priority["("] = 0
+        priority["+"] = 1
+        priority["-"] = 1
+        priority["*"] = 2
+        priority["/"] = 2
+        priority["^"] = 3
 
-        val input = findViewById<TextView>(R.id.input)
+        tokensType["+"] = Tokens.Operations
+        tokensType["-"] = Tokens.Operations
+        tokensType["*"] = Tokens.Operations
+        tokensType["/"] = Tokens.Operations
+        tokensType["^"] = Tokens.Operations
+        tokensType["+"] = Tokens.Operations
+        tokensType["+"] = Tokens.Operations
+        tokensType["("] = Tokens.BracketOpen
+        tokensType[")"] = Tokens.BracketClose
 
-        findViewById<Button>(R.id.btn_0).setOnClickListener { btnInt(it as Button) }
-        findViewById<Button>(R.id.btn_1).setOnClickListener { btnInt(it as Button) }
-        findViewById<Button>(R.id.btn_2).setOnClickListener { btnInt(it as Button) }
-        findViewById<Button>(R.id.btn_3).setOnClickListener { btnInt(it as Button) }
-        findViewById<Button>(R.id.btn_4).setOnClickListener { btnInt(it as Button) }
-        findViewById<Button>(R.id.btn_5).setOnClickListener { btnInt(it as Button) }
-        findViewById<Button>(R.id.btn_6).setOnClickListener { btnInt(it as Button) }
-        findViewById<Button>(R.id.btn_7).setOnClickListener { btnInt(it as Button) }
-        findViewById<Button>(R.id.btn_8).setOnClickListener { btnInt(it as Button) }
-        findViewById<Button>(R.id.btn_9).setOnClickListener { btnInt(it as Button) }
+        constants["π"] = Math.PI
+        constants["e"] = Math.E
 
-        findViewById<Button>(R.id.btn_add).setOnClickListener { btnAct(it as Button) }
-        findViewById<Button>(R.id.btn_sub).setOnClickListener { btnAct(it as Button) }
-        findViewById<Button>(R.id.btn_mul).setOnClickListener { btnAct(it as Button) }
-        findViewById<Button>(R.id.btn_div).setOnClickListener { btnAct(it as Button) }
+        findViewById<Button>(R.id.btn_0).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_1).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_2).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_3).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_4).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_5).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_6).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_7).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_8).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_9).setOnClickListener { btn_listener(it as Button) }
 
-        findViewById<Button>(R.id.btn_equ).setOnClickListener { toRpn() }
-    }
+        findViewById<Button>(R.id.btn_dot).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_add).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_sub).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_mul).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_div).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_bro).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_brc).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_pow).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_sqrt).setOnClickListener { btn_listener(it as Button) }
 
+        findViewById<Button>(R.id.btn_pi).setOnClickListener { btn_listener(it as Button) }
+        findViewById<Button>(R.id.btn_elr).setOnClickListener { btn_listener(it as Button) }
 
-    fun btnInt(btn: Button) {
-        val input = findViewById<TextView>(R.id.input)
-        input.text = input.text.toString() + btn.text
-        tmp_buf += btn.text
+        findViewById<Button>(R.id.btn_x).setOnClickListener { btn_listener(it as Button) }
 
-        act_ena = true
-        findViewById<TextView>(R.id.tmp_buf_out).text = tmp_buf
-        findViewById<TextView>(R.id.buf_out).text = buffer.toString()
-    }
+        findViewById<Button>(R.id.btn_equ).setOnClickListener { btn_listener(it as Button) }
 
-    fun btnAct(btn: Button) {
-        if (act_ena) {
-            val input = findViewById<TextView>(R.id.input)
-            input.text = input.text.toString() + btn.text
-            if (tmp_buf != "") {
-                buffer += tmp_buf
-                tmp_buf = ""
+        val image = findViewById<TextView>(R.id.input)
+
+        findViewById<ImageButton>(R.id.del).setOnClickListener {
+            image.text = image.text.dropLast(1)
+        }
+
+        findViewById<Button>(R.id.btn_sbm).setOnClickListener {
+            findViewById<TextView>(R.id.last_exp_out).text = findViewById<TextView>(R.id.input).text.toString()
+            val equations = findViewById<TextView>(R.id.input).text.toString().split('=')
+            if (equations.size == 1) {
+                val answer = evaluate(toRpn(tokenizer(equations[0])))
+                val value = if (answer.value.toString().split('.')[1] == "0")
+                    (answer.value as Double).toInt().toString()
+                else (answer.value as Double).toFloat().toString()
+                findViewById<TextView>(R.id.left_out).text = answer.toString()
+                findViewById<TextView>(R.id.last_exp_out).text =
+                    findViewById<TextView>(R.id.last_exp_out).text.toString() + " = " + value
+                findViewById<TextView>(R.id.input).text = ""
+            } else {
+                var left = evaluate(toRpn(tokenizer(equations[0])))
+                var right = evaluate(toRpn(tokenizer(equations[1])))
+
+                if (((left.type == Tokens.Number) and (right.type != Tokens.Number)) or
+                    (left.type == Tokens.Linear) and (right.type == Tokens.Quadratic)) {
+                    val tmp = right
+                    left = right
+                    right = tmp
+                }
+
+                findViewById<TextView>(R.id.left_out).text = left.toString()
+                findViewById<TextView>(R.id.right_out).text = right.toString()
+
+                if (left.type == Tokens.Number) {
+                    val value = if (left.value.toString().split('.')[1] == "0")
+                        (left.value as Double).toInt().toString()
+                    else left.value.toString()
+                    findViewById<TextView>(R.id.last_exp_out).text =
+                        findViewById<TextView>(R.id.last_exp_out).text.toString() + " = " + value
+                    findViewById<TextView>(R.id.input).text = ""
+                } else if (left.type == Tokens.Linear) {
+                    val answer: Double
+
+                    answer = if (right.type == Tokens.Number)
+                        (left.value as Linear - right.value as Double).answer()
+                    else
+                        (left.value as Linear - right.value as Linear).answer()
+                    val value: String
+                    value = if (answer.toString().split('.')[1] == "0")
+                        answer.toInt().toString()
+                    else answer.toString()
+                    findViewById<TextView>(R.id.last_exp_out).text =
+                        findViewById<TextView>(R.id.last_exp_out).text.toString() +
+                                "\n${(left.value as Linear).name} = " + value
+                    findViewById<TextView>(R.id.input).text = ""
+                } else {
+
+                }
             }
-            act_ena = false
-            buffer += btn.text.toString()
         }
-        findViewById<TextView>(R.id.buf_out).text = buffer.toString()
     }
 
-    fun toRpn() {
-        if (tmp_buf != "") {
-            buffer += tmp_buf
-            tmp_buf = ""
+
+    private fun tokenizer(exp: String): List<Token> {
+        var position = 0
+        var tokens = listOf<Token>()
+
+        while (position < exp.length) {
+            val chr = exp[position]
+
+            if (chr == ' ') {
+                position++
+                continue
+            } else if ((chr in '0'..'9') or (chr == '.')) {
+                var pos = position
+                while (pos < exp.length) {
+                    if (!((exp[pos] in '0'..'9') or (exp[pos] == '.')))
+                        break
+                    pos++
+                }
+                if (tokens.isNotEmpty()) {
+                    if (tokens.last().type in arrayOf(Tokens.BracketClose, Tokens.Constant, Tokens.Variable))
+                        tokens += Token(Tokens.Operations, "*")
+                }
+                tokens += Token(Tokens.Number, exp.substring(position, pos).toDouble())
+                position = pos
+            } else if (chr == 'X') {
+                if (tokens.isNotEmpty()) {
+                    if (tokens.last().type in arrayOf(Tokens.BracketClose, Tokens.Constant, Tokens.Number))
+                        tokens += Token(Tokens.Operations, "*")
+                }
+                tokens += Token(Tokens.Variable, chr.toString())
+                position++
+            } else if (chr.toString() in constants.keys){
+                if (tokens.isNotEmpty()) {
+                    if (tokens.last().type in arrayOf(Tokens.BracketClose, Tokens.Constant, Tokens.Variable, Tokens.Number))
+                        tokens += Token(Tokens.Operations, "*")
+                }
+                tokens += Token(Tokens.Constant, chr.toString())
+                position++
+            } else if (chr in 'a'..'z') {
+                var pos = position
+                while (pos < exp.length) {
+                    if (exp[pos] !in 'a'..'z')
+                        break
+                    pos++
+                }
+                if (tokens.isNotEmpty()) {
+                    if (tokens.last().type in arrayOf(Tokens.BracketClose, Tokens.Constant, Tokens.Variable))
+                        tokens += Token(Tokens.Operations, "*")
+                }
+                tokens += Token(Tokens.Function, exp.substring(position, pos))
+                position = pos
+            }
+            else if (tokensType.containsKey(chr.toString())) {
+                if (tokens.isNotEmpty()) {
+                    if ((tokensType[chr.toString()]!! == Tokens.BracketOpen) and (tokens.last().type == Tokens.Number))
+                        tokens += Token(Tokens.Operations, "*")
+                    if ((chr == '-') and (tokens.last().type != Tokens.Number))
+                        tokens += Token(Tokens.Number, 0.toDouble())
+                } else if (chr == '-')
+                    tokens += Token(Tokens.Number, 0.toDouble())
+                tokens += Token(tokensType[chr.toString()]!!, chr.toString())
+                position++
+            } else {
+                findViewById<TextView>(R.id.input).error = "Неизвестный символ: ${exp[position]}"
+                break
+            }
         }
-        findViewById<TextView>(R.id.tmp_buf_out).text = tmp_buf
-        findViewById<TextView>(R.id.buf_out).text = buffer.toString()
 
-        var out_buf = listOf<String>()
-        var act_stc = listOf<String>()
+        var new_tokens = listOf<Token>()
 
-        Log.d("Meow!", buffer.toString())
+        for (token in tokens) {
+            if (token.type == Tokens.Constant) {
+                new_tokens += Token(Tokens.Number, constants[token.value]!!)
+            } else {
+                new_tokens += token
+            }
+        }
 
-        for (token in buffer) {
-            if (token.toBigDecimalOrNull() != null)
+        Log.i("Meow!", new_tokens.toString())
+        return new_tokens
+    }
+
+    private fun btn_listener(btn: Button) {
+        val input = findViewById<TextView>(R.id.input)
+        input.text = input.text.toString() + btn.text.toString()
+    }
+
+    fun toRpn(tokens: List<Token>): List<Token> {
+        var out_buf = listOf<Token>()
+        val act_buf = arrayListOf<Token>()
+
+        for (token in tokens) {
+            if (token.type in arrayOf(Tokens.Number, Tokens.Variable))
                 out_buf += token
-            else if (token in listOf<String>("+", "-", "*", "/")) {
-//                if (act_stc.lastOrNull() == null)
-//                    act_stc += token
-//                else if (priority[token]!! > priority[act_stc.last()]!!)
-//                    act_stc += token
-//                else {
-//                    out_buf += act_stc.last()
-//                    act_stc = act_stc.dropLast(1)
-//                    act_stc += token
-//                }
-
-                if (act_stc.lastOrNull() != null) {
-                    while (priority[token]!! <= priority[act_stc.last()]!!) {
-                        out_buf += act_stc.last()
-                        act_stc = act_stc.dropLast(1)
-
-                        if (act_stc.isEmpty())
+            else if (token.type == Tokens.Function)
+                act_buf += token
+            else if (token.type == Tokens.Operations) {
+                if (act_buf.lastOrNull() != null) {
+                    while (
+                        (priority[token.value]!! < priority[act_buf.last().value]!!) or
+                        ((priority[token.value]!! == priority[act_buf.last().value]!!) and
+                                (token.value in leftAssociative))) {
+                        out_buf += act_buf.removeLast()
+                        if (act_buf.isEmpty())
                             break
                     }
                 }
-                act_stc += token
+                act_buf += token
+            } else if (token.type == Tokens.BracketOpen)
+                act_buf += token
+            else if (token.type == Tokens.BracketClose){
+                while (act_buf.last().type != Tokens.BracketOpen)
+                    out_buf += act_buf.removeLast()
+                act_buf.removeLast()
+                if (act_buf.lastOrNull() != null) {
+                    if (act_buf.last().type == Tokens.Function)
+                        out_buf += act_buf.removeLast()
+                }
             }
-            Log.d("Meow!", "Act: $act_stc\tOut: $out_buf")
+
+            Log.d("Meow!", "Act: $act_buf\tOut: $out_buf")
         }
 
-        out_buf += act_stc.reversed()
+        out_buf += act_buf.reversed()
         findViewById<TextView>(R.id.RPN_out).text = out_buf.toString()
-
-        tmp_buf = ""
-        buffer = listOf()
-        act_ena = false
         findViewById<TextView>(R.id.input).text = ""
+
+        Log.d("Meow!", "toRpn: $out_buf")
+        return out_buf
     }
+
+    fun evaluate(ext: List<Token>): Token {
+        var position = 0
+        var buffer = ext
+        var tmp_buf = listOf<Token>()
+
+        while (buffer.size != 1) {
+            val token = buffer[position]
+
+            if (token.type == Tokens.Function) {
+                if (token.value == "sqrt") {
+                    tmp_buf = buffer.dropLast(ext.size - position + 1)
+                    var res = Token(Tokens.Number, sqrt(buffer[position - 1].value as Double))
+                    tmp_buf += res
+                    tmp_buf += buffer.drop(position+1)
+                }
+            } else if (token.type == Tokens.Operations) {
+                val first = buffer[position-2]
+                val second = buffer[position-1]
+
+                //TODO: make operations with other objects
+                if (token.value == "+") {
+                    tmp_buf = buffer.dropLast(ext.size - position + 2)
+                    var res: Token
+                    if ((first.type == Tokens.Number) and (second.type == Tokens.Number))
+                        res = Token(Tokens.Number, (first.value as Double + second.value  as Double))
+                    else if ((first.type == Tokens.Variable) and (second.type == Tokens.Number))
+                        res = Token(Tokens.Linear, Linear(first.value as String, second.value as Double, 0.toDouble()))
+                    else
+                        res = Token(Tokens.Linear, Linear(second.value as String, first.value as Double, 0.toDouble()))
+                    tmp_buf += res
+                    tmp_buf += buffer.drop(position+1)
+                } else if (token.value == "-") {
+                    tmp_buf = buffer.dropLast(ext.size - position + 2)
+                    val res = Token(Tokens.Number, (first.value as Double - second.value as Double))
+                    tmp_buf += res
+                    tmp_buf += buffer.drop(position+1)
+                } else if (token.value == "*") {
+                    tmp_buf = buffer.dropLast(ext.size - position + 2)
+                    val res: Token
+                    res = if ((first.type == Tokens.Number) and (second.type == Tokens.Number))
+                        Token(Tokens.Number, first.value as Double*second.value as Double)
+                    else if ((first.type == Tokens.Number) and (second.type == Tokens.Variable))
+                        Token(Tokens.Linear, Linear(second.value as String, 0.toDouble(), first.value as Double))
+                    else if ((first.type == Tokens.Variable) and (second.type == Tokens.Number))
+                        Token(Tokens.Linear, Linear(first.value as String, 0.toDouble(), second.value as Double))
+                    else //if ((first.type == Tokens.Variable) and (second.type == Tokens.Variable))
+                        Token(Tokens.Quadratic, Quadratic(first.value as String, 0.toDouble(), 0.toDouble(), 2.toDouble()))
+                    tmp_buf += res
+                    tmp_buf += buffer.drop(position+1)
+                } else if (token.value == "/") {
+                    tmp_buf = buffer.dropLast(ext.size - position + 2)
+                    val res = Token(Tokens.Number, first.value as Double/second.value as Double)
+                    tmp_buf += res
+                    tmp_buf += buffer.drop(position+1)
+                } else if (token.value == "^") {
+                    tmp_buf = buffer.dropLast(ext.size - position + 2)
+                    val res = Token(
+                        Tokens.Number, (first.value as Double)
+                            .pow(second.value as Double)
+                    )
+                    tmp_buf += res
+                    tmp_buf += buffer.drop(position + 1)
+                }
+            } else {
+                position++
+                continue
+            }
+
+            buffer = tmp_buf
+            position = 0
+            Log.d("Meow!", buffer.toString())
+        }
+
+        return buffer[0]
+    }
+
+}
+
+enum class Tokens {
+    Number,
+    Operations,
+    Function,
+    BracketOpen,
+    BracketClose,
+    Constant,
+    Variable,
+    Linear,
+    Quadratic
+}
+
+class Token (val type: Tokens, var value: Any) {
+    override fun toString(): String {
+        return "<$type, $value>"
+    }
+}
+
+open class MathObject(val value: Any) {
+    operator fun minus(num: MathObject): MathObject {
+        return MathObject(value)
+    }
+}
+
+class Linear(val name: String, private val add: Double, private val mul: Double) : MathObject("$mul*$name+$add") {
+    //TODO: Implement more methods
+    override fun toString(): String {
+        return "$mul*$name+$add"
+    }
+
+    operator fun minus(num: Double): Linear {
+        return Linear(name, add-num, mul)
+    }
+
+    operator fun minus(lin: Linear): Linear {
+//        if (name != lin.name) throw IllegalArgumentException
+        return Linear(name, add-lin.add, mul-lin.mul)
+    }
+
+    fun answer() = -add/mul
+}
+
+class Quadratic(name: String, add: Double, mul: Double, pow: Double) {
+    //TODO: Implement more methods
 }
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index 00e4467..879bf4d 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -14,29 +14,117 @@
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
-    <TextView
-        android:id="@+id/tmp_buf_out"
-        android:layout_width="0dp"
-        android:layout_height="wrap_content"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/input" />
-
-    <TextView
-        android:id="@+id/buf_out"
-        android:layout_width="0dp"
-        android:layout_height="wrap_content"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/tmp_buf_out" />
-
     <TextView
         android:id="@+id/RPN_out"
         android:layout_width="0dp"
         android:layout_height="wrap_content"
         app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/last_exp_out" />
+
+    <TextView
+        android:id="@+id/left_out"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/RPN_out" />
+
+    <TextView
+        android:id="@+id/right_out"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/left_out" />
+
+    <ScrollView
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        app:layout_constraintBottom_toTopOf="@+id/linearLayout2"
+        app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/buf_out" />
+        app:layout_constraintTop_toBottomOf="@+id/RPN_out">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical" >
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:orientation="vertical">
+
+                <Button
+                    android:id="@+id/btn_sbm"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:text="Вычислить" />
+
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent"
+                    android:orientation="horizontal">
+
+                    <Button
+                        android:id="@+id/btn_x"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="1"
+                        android:text="X" />
+
+                    <Button
+                        android:id="@+id/btn_pi"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="1"
+                        android:text="π" />
+
+                    <Button
+                        android:id="@+id/btn_elr"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="1"
+                        android:text="e" />
+                </LinearLayout>
+
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent"
+                    android:orientation="horizontal">
+
+                    <Button
+                        android:id="@+id/btn_bro"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="1"
+                        android:text="(" />
+
+                    <Button
+                        android:id="@+id/btn_brc"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="1"
+                        android:text=")" />
+
+                    <Button
+                        android:id="@+id/btn_pow"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="1"
+                        android:text="^" />
+
+                    <Button
+                        android:id="@+id/btn_sqrt"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="1"
+                        android:text="sqrt" />
+
+                </LinearLayout>
+
+            </LinearLayout>
+
+        </LinearLayout>
+    </ScrollView>
 
     <LinearLayout
         android:id="@+id/linearLayout2"
@@ -49,7 +137,7 @@
 
         <LinearLayout
             android:id="@+id/linearLayout"
-            android:layout_width="match_parent"
+            android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:orientation="vertical">
 
@@ -62,21 +150,18 @@
                     android:id="@+id/btn_1"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:layout_weight="1"
                     android:text="1" />
 
                 <Button
                     android:id="@+id/btn_2"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:layout_weight="1"
                     android:text="2" />
 
                 <Button
                     android:id="@+id/btn_3"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:layout_weight="1"
                     android:text="3" />
             </LinearLayout>
 
@@ -89,21 +174,18 @@
                     android:id="@+id/btn_4"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:layout_weight="1"
                     android:text="4" />
 
                 <Button
                     android:id="@+id/btn_5"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:layout_weight="1"
                     android:text="5" />
 
                 <Button
                     android:id="@+id/btn_6"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:layout_weight="1"
                     android:text="6" />
 
             </LinearLayout>
@@ -117,21 +199,18 @@
                     android:id="@+id/btn_7"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:layout_weight="1"
                     android:text="7" />
 
                 <Button
                     android:id="@+id/btn_8"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:layout_weight="1"
                     android:text="8" />
 
                 <Button
                     android:id="@+id/btn_9"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:layout_weight="1"
                     android:text="9" />
 
             </LinearLayout>
@@ -148,30 +227,19 @@
                     android:text="0" />
 
                 <Button
-                    android:id="@+id/btn_bro"
+                    android:id="@+id/btn_dot"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:text="(" />
+                    android:text="." />
 
-                <Button
-                    android:id="@+id/btn_brc"
-                    android:layout_width="wrap_content"
-                    android:layout_height="wrap_content"
-                    android:text=")" />
-
-                <Button
-                    android:id="@+id/btn_equ"
-                    android:layout_width="wrap_content"
-                    android:layout_height="wrap_content"
-                    android:layout_marginBottom="8dp"
-                    android:text="=" />
             </LinearLayout>
 
         </LinearLayout>
 
         <LinearLayout
-            android:layout_width="match_parent"
+            android:layout_width="wrap_content"
             android:layout_height="wrap_content"
+            android:layout_weight="1"
             android:orientation="vertical">
 
             <Button
@@ -203,8 +271,36 @@
                 android:text="/" />
         </LinearLayout>
 
+        <LinearLayout
+            android:layout_width="wrap_content"
+            android:layout_height="match_parent"
+            android:layout_weight="1"
+            android:orientation="vertical">
+
+            <Button
+                android:id="@+id/btn_equ"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginBottom="8dp"
+                android:text="=" />
+
+            <ImageButton
+                android:id="@+id/del"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                app:srcCompat="@android:drawable/ic_input_delete" />
+        </LinearLayout>
+
     </LinearLayout>
 
+    <TextView
+        android:id="@+id/last_exp_out"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/input" />
+
     <!--    <EditText-->
 <!--        android:id="@+id/function_in"-->
 <!--        android:layout_width="0dp"-->