Start by simply putting rods together to measure different lengths. As you explore, you may make some discoveries that will lead you into the world of number theory.

Watch our videos to see how we measured different lengths with sets of rods. Then explore which sets of rods are best for measuring longer and longer lengths...

If we only had 3p and 7p coins, there'd be some values that we couldn't make. I wonder which ones? Explore this question and find out all about theFrobenius coin problem.