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Where Can We Visit?

Charlie and Abi put a counter on 42. They wondered if they could visit all the other numbers on their 1-100 board, moving the counter using just these two operations: x2 and -5. What do you think?

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Babylon Numbers

Can you make a hypothesis to explain these ancient numbers?

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Ishango Bone

Can you decode the mysterious markings on this ancient bone tool?

How Much Can We Spend?

Age 11 to 14 Challenge Level:

8z (3+5)
9z (3+3+3)
10z (5+5)
11z (3+3+5)
12z (3+3+3+3)
13z (3+5+5)
14z (3+3+3+5)...

What do you notice about 8z, 11z, 14z......?