We know that,
Area of circle is 3.14*r*r
r=input("Enter radius of circlen")
print("Area of circle is "+str(area))
Enter radius of circle
Area of circle is 28.259999999999998
In this progra, firstly we take radius as a input from the user, in python input things are always a string so firstly we convert it into the integer to use the radius so we do type casting by the use of int. then we calculate the area and store in vaiable 'area' then we print area.