Novice · Arithmetic · 28 of 264
Circle area
Read the radius of a circle and print its area with two decimals. Use math.pi: start with import math.
Input: a whole number, the radius. Output: the area (pi * r * r), two decimals.
Examples
Input
1
Output
3.14
Input
2
Output
12.57
Input
10
Output
314.16
One more test checks other inputs when you press Check.
Stuck? The idea behind arithmetic
input() always gives text: turn it into a whole number with int() or a decimal with float() before doing sums.
+ - * / work as in maths; / always gives a decimal. // divides and drops the remainder, % gives the remainder, ** raises to a power.
a = int(input()) b = int(input()) print(a + b) print(a // b, a % b)
Watch for: "5" + "3" is "53", not 8: if a sum joins numbers together, an int() is missing.