1. Add calculator app using Kivy.

2. Update README.md to include Kivy calculator app.

Author: aditya7balotra

README.md

@@ -55,6 +55,7 @@ Feel free to explore the scripts and use them for your learning and automation n
 40. [Test Case Generator](https://github.com/Tanmay-901/test-case-generator/blob/master/test_case.py) - Generate different types of test cases with a clean and friendly UI, used in competitive programming and software testing.
 41. [Extract Thumbnail From Video](https://github.com/geekcomputers/Python/tree/ExtractThumbnailFromVideo) - Extract Thumbnail from video files
 42. [How to begin the journey of open source (first contribution)](https://www.youtube.com/watch?v=v2X51AVgl3o) - First Contribution of open source
+43. [kivy_calculator.py](https://github.com/geekcomputers/Python/blob/master/kivy_calculator.py) - Calculator UI using Kivy
 <hr>
 
-_**Note**: The content in this repository belongs to the respective authors and creators. I'm just providing a formatted README.md for better presentation._
+_**Note**: The content in this repository belongs to the respective authors and creators. I'm just providing a formatted README.md for better presentation._

kivy_calculator.py

@@ -0,0 +1,119 @@
+"""
+
+wanna try some GUI based calculator, here is one!
+Try it, brake it. If you find some bug and have better way ahead, i welcome your change :)
+
+Install dependencies:
+    pip install kivy==2.3.1 kivymd==1.1.1
+
+"""
+
+from kivymd.app import MDApp
+from kivymd.uix.button import MDFlatButton  # Fixed F403
+from kivy.lang import Builder
+
+opt = ["(", ")", "X", "/", "+", "-"]
+opt_check = ["X", "/", "+", "-"]
+
+cal = """
+MDScreen:
+    MDBoxLayout:
+        orientation:'vertical'
+        MDLabel:
+            text:'I welcome you!'
+            adaptive_height:True
+            halign:'center'
+
+        MDTextField:
+            id:field
+            
+            font_size:dp(60)
+            pos_hint:{'top':1}
+            size_hint_x:1
+            size_hint_y:.4
+            readonly:True
+            multiline:True
+
+        MDGridLayout:
+            id:grid
+            cols:4
+"""
+
+
+class calculator(MDApp):
+
+    def build(self):
+        self.theme_cls.theme_style = "Dark"
+        return Builder.load_string(cal)
+
+    def on_start(self):
+
+        self.root.ids.grid.add_widget(
+            MDFlatButton(text="AC", on_release=self.delete_all, size_hint=[1, 1])
+        )
+        self.root.ids.grid.add_widget(
+            MDFlatButton(text="del", on_release=self.delete, size_hint=[1, 1])
+        )
+        self.root.ids.grid.add_widget(
+            MDFlatButton(text="^", on_release=self.to_field, size_hint=[1, 1])
+        )
+
+        for i in range(len(opt)):
+            self.root.ids.grid.add_widget(
+                MDFlatButton(
+                    text=opt[i], on_release=self.to_field_opt, size_hint=[1, 1]
+                )
+            )
+
+        for i in range(10):
+            self.root.ids.grid.add_widget(
+                MDFlatButton(text=str(i), on_release=self.to_field, size_hint=[1, 1])
+            )
+
+        self.root.ids.grid.add_widget(
+            MDFlatButton(text="=", on_release=self.calculate, size_hint=[1, 1])
+        )
+
+    def to_field(self, btn):
+        if self.root.ids.field.text == "undefined":
+            self.root.ids.field.text = ""
+        self.root.ids.field.text = self.root.ids.field.text + btn.text
+
+    def to_field_opt(self, btn):
+        if self.root.ids.field.text == "undefined":
+            self.root.ids.field.text = ""
+
+        elif btn.text != "(" and btn.text != ")" and self.root.ids.field.text == "":
+            self.root.ids.field.text = f"0+{btn.text}"
+
+        elif self.root.ids.field.text != "" and btn.text in opt_check:
+            if self.root.ids.field.text[-1] in opt_check:
+                self.root.ids.field.text = self.root.ids.field.text[:-1] + btn.text
+            else:
+                self.root.ids.field.text = self.root.ids.field.text + btn.text
+
+        else:
+            self.root.ids.field.text = self.root.ids.field.text + btn.text
+
+    def delete_all(self, del_all_btn):
+        self.root.ids.field.text = ""
+
+    def delete(self, del_btn):
+        self.root.ids.field.text = self.root.ids.field.text[:-1]
+
+    def calculate(self, cal_btn):
+        ch_opt_list = ["X", "^"]
+        with_opt = ["*", "**"]
+        raw = self.root.ids.field.text
+
+        for opt in ch_opt_list:
+            raw = raw.replace(opt, with_opt[ch_opt_list.index(opt)])
+
+        try:
+            self.root.ids.field.text = str(eval(raw))
+        except Exception:  # Fixed E722
+            self.root.ids.field.text = "undefined"
+
+
+if __name__ == "__main__":
+    calculator().run()