Beginner · For loops · 71 of 264
Factorial
The factorial of n is 1 * 2 * ... * n, and the factorial of 0 is 1. Compute it with a loop.
Input: a whole number n from 0 to 20. Output: n!
Examples
Input
5
Output
120
Input
0
Output
1
Input
1
Output
1
2 more tests check other inputs when you press Check.
Stuck? The idea behind for loops
A for loop repeats its indented lines once for each item: each letter of a string, each item of a list, or each number of a range.
range(5) is 0 to 4; range(1, 6) is 1 to 5; range(10, 0, -1) counts down from 10 to 1.
total = 0
for i in range(1, 6):
total += i
print(total) # 15Watch for: range stops before its end: range(1, n) leaves out n. A print inside the loop prints every time; outside it (not indented), once at the end.