Problem Solving in 3F

Today we read a book about a wise man in India who did the king a favour. The king wanted to repay him so the wiseman told him he should give him some rice, starting with one grain and doubling each day for each square on his chessboard. The king didn’t know how much rice this was but was too proud to ask. OOPS. We know this never goes well.

Turns out when you double numbers 64 times they get BIG!

We explored what would happen if the chess board had 25 squares. students used a mix of their own knowledge, addition strategies and calculators to find out that at the end of 25 days the king had given away 16 777 216 grains of rice.


Some of the students finished this easily so I challenged them to start exploring how much rice would be owed on the 64th day. One group got a little hooked… I don’t think they did much else today. We got really excited when they hit trillions, then it just kept going! I’m not ashamed to say i had to resort to Google after quadrillion!


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