Prime Order

Weekly Problem 24 - 2006
How many of the rearrangements of the digits 1, 3 and 5 give prime numbers?
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
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Problem



How many of the three-digit numbers that can be made from all of the digits 1, 3 and 5 (used only once each) are prime?

 

If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.