# Math :/

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A light flashes every 15 minutes. a second light flashes every 18 minutes. both lights flash together are 2 a.m. What will the time be when they net flash together?

• Math :/ -

1st light:
15 30 45 90 ...
2nd light:
18 36 54 72 90....
ahhh!!

So what is 90 minutes from 2:00 am ?

another way to look at it ...
What is the LCM for 15 and 18 ?

• Math :/ -

90

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