diff --git a/calculator.py b/calculator.py
index 6f0f018c..0d773866 100644
--- a/calculator.py
+++ b/calculator.py
@@ -1,59 +1,52 @@
-num1=int(input("eneter a digit"))
-num2=int(input("eneter a another digit"))
-# defination for operators
-
-#addition
-def add(num1, num2):
-    return num1+num2
-#substraction
-def subtract(num1, num2):
-    return num1-num2
-#multiply
-def multiply(num1, num2):
-    return num1*num2
-#division
-def divide(num1, num2):
-    return num1/num2
-
-#command for operation
-print("choose operation")
-print("press 1 for add")
-print("press 2 for subs")
-print("press 3 for multiply")
-print("press 4 for devision")
-
-
-
-
-
-while True:
-    # take input from the user
-    choice = input("Enter choice(1/2/3/4): ")
-
-    if choice in ('1', '2', '3', '4'):
-
-        if choice == '1':
-            print(num1, "+", num2, "=", add(num1, num2))
-
-
-
-        elif choice == '2':
-            print(num1, "-", num2, "=", subtract(num1, num2))
-
-        elif choice == '3':      
-            print(num1, "*", num2, "=", multiply(num1, num2))
-
-
-
-
-
-        elif choice == '4':
-            print(num1, "/", num2, "=", divide(num1, num2))
-        # check if user wants another calculation
-        # break the while loop if answer is no
-        next_calculation = input("Let's do next calculation? (yes/no): ")
-        if next_calculation == "no":
-            break
-
-    else:
-        print("Invalid Input")
+# This function adds two numbers
+def add(x, y):
+    return x + y
+
+# This function subtracts two numbers
+def subtract(x, y):
+    return x - y
+
+# This function multiplies two numbers
+def multiply(x, y):
+    return x * y
+
+# This function divides two numbers
+def divide(x, y):
+    return x / y
+
+
+print("Select operation.")
+print("1.Add")
+print("2.Subtract")
+print("3.Multiply")
+print("4.Divide")
+
+while True:
+    # take input from the user
+    choice = input("Enter choice(1/2/3/4): ")
+
+    # check if choice is one of the four options
+    if choice in ('1', '2', '3', '4'):
+        num1 = float(input("Enter first number: "))
+        num2 = float(input("Enter second number: "))
+
+        if choice == '1':
+            print(num1, "+", num2, "=", add(num1, num2))
+
+        elif choice == '2':
+            print(num1, "-", num2, "=", subtract(num1, num2))
+
+        elif choice == '3':
+            print(num1, "*", num2, "=", multiply(num1, num2))
+
+        elif choice == '4':
+            print(num1, "/", num2, "=", divide(num1, num2))
+        
+        # check if user wants another calculation
+        # break the while loop if answer is no
+        next_calculation = input("Let's do next calculation? (y/n): ")
+        if next_calculation == "n":
+          break
+    
+    else:
+        print("Invalid Input")
\ No newline at end of file
diff --git a/longestcommonprefix.py b/longestcommonprefix.py
new file mode 100644
index 00000000..cff15269
--- /dev/null
+++ b/longestcommonprefix.py
@@ -0,0 +1,33 @@
+def longestCommonPrefix(a):
+      
+    size = len(a)
+  
+    # if size is 0, return empty string 
+    if (size == 0):
+        return ""
+  
+    if (size == 1):
+        return a[0]
+  
+    # sort the given strings
+    a.sort()
+      
+    # find the minimum length string
+    end = min(len(a[0]), len(a[size - 1]))
+  
+    # find the common prefix 
+    i = 0
+    while (i < end and a[0][i] == a[size - 1][i]):
+        i += 1
+  
+    ans = a[0][0: i]
+    return ans
+  
+inputs = []
+
+n = int(input("Enter the number of strings : "))
+
+for i in range(n):
+  inputs.append(input("Enter the string : "))
+
+print("The longest Common Prefix is :" , longestCommonPrefix(inputs))
\ No newline at end of file