Question

Wasim's mom asks him to clean his room every 6 days, and wash his windows every 15 days. If he does them both today, when is the NEXT time he will be cleaning his room and washing his windows on the same day?

Answer 1

30 days

Explanation:

We solve the above question using Lowest Common Multiple Method.

Find and list multiples of each number until the first common multiple is found. This is the lowest common multiple.

Multiples of 6:

6, 12, 18, 24, 30, 36, 42

Multiples of 15:

15, 30, 45, 60

Therefore,

LCM(6, 15) = 30

Therefore, the NEXT time he will be cleaning his room and washing his windows on the same day is in 30 days time