simplecalc.py

print("Press 1 to add two numbers, 2 to subtract, 3 to multiply, 4 to divide")

a = int(input())
#Note: Generally input is interpreted as a string.
#Therefore I am converting that to integer

if a == 1:
	b = float(input("First number:	"))
	#Note:In the above line the input is converted to a float
	c = float(input("Second number:	"))
	print("The sum is", b + c)
elif a == 2:
	print("Only addition is implemented. Subtraction is left to be implemented by Tias")
elif a == 3:
	print("Only addition is implemented. Multiplication is left to be implemented by Tias")
elif a == 4:
	print("Only addition is implemented. Division is left to be implemented by Tias")
else:
	print("Error. Input must be either 1,2,3,4")