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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?

Babylon Numbers

Can you make a hypothesis to explain these ancient numbers?

Ishango Bone

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

Arithmagons

Age 11 to 16 Challenge Level:

How does the sum of the numbers at the edges relate to the sum of the numbers at the vertices?  

It might help to label the numbers at the vertices $A$, $B$ and $C$ and then express the edge numbers in terms of $A$, $B$ and $C$.