How many consecutive numbers do you need to guarantee that one of the numbers is divisible by 5?

Question

Consecutive numbers to guarantee that one is divisible by 5.

Answer 1

1,2,3,4,5

6,7,8,9,10

11,12,13,14,15

16,17,18,19,20

you need 5 consecutive whole numbers to guarantee a number divisible by 5

every fifth number is a multiple of 5

it can't be only 2 numbers because although you might pick 9 and 10, you might also pick 12 and 13

it can't be only 3 because you could pick 17, 18, and 19 instead of 23, 24, and 25

it can't be only 4 because you might pick 31, 32, 33, and 34

it has to be 5 and one will guaranteed to be divisible by 5