diff --git a/README_POPOV.md b/README_POPOV.md
new file mode 100644
index 0000000..061688b
--- /dev/null
+++ b/README_POPOV.md
@@ -0,0 +1,42 @@
+# Calculator
+
+This readme describes mini-program Calculator you can find here.
+
+Calculator can calculate easy arythmetical functions:
+* Addition
+* Subtraction
+* Multiplication
+* Division
+
+## How it works
+
+1. Clone this repo using SSH or HTTPS:
+
+```bash
+git clone git@github.com:YuryPopov/HW2_Git_and_python.git
+``` 
+**or**
+```bash
+git clone https://github.com/YuryPopov/HW2_Git_and_python.git
+``` 
+2. Launch application (I hope, that you are inside app folder):
+```bash
+python3 ./calculator.py
+```
+3. After prompt (*Enter expression:*) enter your expression (numbers and arythmetical operator divided with spaces) and press *"Enter"* button.
+***Pay attention***, programm works with integrer and float numbers and only with +, -, *, / operators.
+**Enter expression like
+```
+1 + 3
+```
+4. Enjoy the results.
+
+
+## Your developers:
+* Yury Popov
+* Kristina Zhur
+* Maria Uzun
+* Anastasia Shtompel
+* Alina Potyseva
+
+![Our team](/images/picture.jpg "Our team")
\ No newline at end of file
diff --git a/calculator.py b/calculator.py
new file mode 100644
index 0000000..c8a5be7
--- /dev/null
+++ b/calculator.py
@@ -0,0 +1,64 @@
+def substract(a, b):
+    return a - b
+
+
+def divide(a, b):
+    if b == 0:
+        return "Error: division by zero"
+    return a / b
+
+
+def multiplication(a, b):
+    answer = a * b
+    return answer
+
+
+def summing(a, b):
+    return a + b
+
+
+list_of_operators = ['/', '*', '-', '+']
+
+
+def main(keyboard_input: str) -> float:
+    '''
+    Function checks operators, transform numbers to float,
+    call math function described above (substract, divide,
+    multiplication, summing) and return result. If operators
+    are not in list or numbers cannot transform into floats,
+    func returns error message.
+    '''
+    math_sign, operator_position = False, False
+    
+    for char in range(len(keyboard_input)):
+        if keyboard_input[char] in list_of_operators:
+            math_sign = keyboard_input[char]
+            operator_position = char
+            
+    if math_sign == False:
+        return 'Enter valid expression'
+    
+    num1 = keyboard_input[:operator_position].strip()
+    num2 = keyboard_input[operator_position + 1:].strip()
+
+    try:
+        num1 = float(num1)
+        num2 = float(num2)
+        if math_sign == '/':
+            return divide(num1, num2)
+
+        elif math_sign == '-':
+            return substract(num1, num2)
+
+        elif math_sign == '+':
+            return summing(num1, num2)
+
+        elif math_sign == '*':
+            return multiplication(num1, num2)
+
+    except ValueError:
+        return 'Enter valid expression'
+
+
+if __name__ == '__main__':
+    print(main(input('Enter expression:')))
diff --git a/images/picture.jpg b/images/picture.jpg
new file mode 100644
index 0000000..4970e37
Binary files /dev/null and b/images/picture.jpg differ
diff --git a/images/picture.jpg:Zone.Identifier b/images/picture.jpg:Zone.Identifier
new file mode 100644
index 0000000..289271c
--- /dev/null
+++ b/images/picture.jpg:Zone.Identifier
@@ -0,0 +1,3 @@
+[ZoneTransfer]
+ZoneId=3
+HostUrl=https://web.telegram.org/