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Beginner · For loops · 69 of 264

Sum from 1 to n

Read n and print 1 + 2 + ... + n, using a loop.

Input: a positive whole number n. Output: the sum.

Examples

Input
10
Output
55
Input
1
Output
1
Input
100
Output
5050

One more test checks 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)  # 15

Watch 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.

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