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A merchant brings four bars of gold to a jeweller. The jeweller suspects that one bar is a fake, and knows that it will be slightly lighter than the real ones.
He only has to use the balance twice before he finds the fake bar. How does he do it?
Now, can you do it with nine bars of gold (one fake light one), again only using the balance twice?
This practical challenge invites you to investigate the different squares you can make on a square geoboard or pegboard.