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A Long Time at the Till

Stage: 4 and 5 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Here are some hints: Prime factorisation will probably be useful, as will working in pence rather than pounds and pence.
There are lots of different possibilities to consider, so you will need to be clear with your recording system.
To get a feel for the complexity, it is very unlikely that you will be able to solve the first part of the problem in under two hours.
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