Math
posted by Sandy on .
I get a black strip every 10 days. A white strip every 20 days, and a red strip every 21 days. I just got all 3 strips. How long 'till I get all of them again on the same day?

What is 7*3*2*5?

210
posted by Sandy on .
I get a black strip every 10 days. A white strip every 20 days, and a red strip every 21 days. I just got all 3 strips. How long 'till I get all of them again on the same day?
What is 7*3*2*5?
210