Puzzles & Quizzes

# Can You Solve This Tricky Math Problem for 8-Year-Olds?

It's a parental nightmare not to be able to figure out your kid's math homework, especially when they're in elementary school. Yet that's exactly what went down for one mother — and a slew of other confused internet users — last month. The problem, originally posted as a photo on the parents' forum Mumsnet, may be a little more difficult than you'd expect an 8-year-old student to be assigned in class.

Scroll down to read the problem and the solution. No judgment if it trips you up a bit.

## Here's the Problem

On the coast, there are three lighthouses.

The first light shines for three seconds, then is off for three seconds.

The second light shines for four seconds, then is off for four seconds.

The third light shines for five seconds, then is off for five seconds.

All three lights have just come on together.

When is the first time that all three lights will be off together?

When is the next time that all three lights will come on at exactly the same moment?

Give this math problem a shot, then scroll down for the answer.