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Let's say you can only use two different lengths - 2 units and 4 units. Using just these 2 lengths as the edges how many different cuboids can you make? ### Two and Two

How many solutions can you find to this sum? Each of the different letters stands for a different number.

# Counting Cogs

##### Age 7 to 14 Challenge Level:
Which pairs of cogs have you found that work?
Which pairs didn't work?
Do you get a sense of why?
What do you notice about the numbers of teeth in each case?
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