# Number Sense Blog

By Mathnasium | Added Nov 6, 2019

Nothing “flashy” here, but we have a great word problem challenge that we think you’ll love! Don’t worry that the problem will “bug” you, it’s so much fun that it will “light” up your day! At our math learning centers for kids, we make math fun so students can learn in a way that makes sense to them.
Today’s challenge highlights multiplication, lowest common denominator, giving students an opportunity to practice and strengthen these and other elementary level math skills. Check out the question below and let your curiosity take control.

Question: One firefly blinks its light once every 8 seconds. Another firefly blinks its light every 9 seconds. If both fireflies blink at the same time, how long will it be before they synchronize blinks again?

Give yourself time to work out the answer, and when you're ready check below to compare your solution to ours.

Solution: We can find the amount of time it’ll take for the fireflies to blink simultaneously by finding the lowest common denominator of 8 and 9; 8 and 9 are relatively prime, so their lowest common denominator is their product. The product of 8 and 9 is 72, so it will take 72 seconds for the fireflies to synchronize again.

### Favorites

Bedtime Math: http://bedtimemath.org/

National PTA: http://www.pta.org/

NCTM: http://www.nctm.org/

Numberphile: http://www.numberphile.com/

PTO Today: http://www.ptotoday.com/

STEM Connector: http://blog.stemconnector.org/

Before I came to Mathnasium, I could sum up everything I felt about math in one word: 'EVIL!' I hated math. ... Mathnasium has been my safe haven. They truly have shown me the light when it came to addressing my fear and provided me with the tools that I need to rebuild my prior knowledge so that I won't forget it. Math is no longer a subject I shy away from but it is a subject I can boldly accept and understand.