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Question from Robin, a student:

hello - my question is:
what is the units digit of (13) to 4; (17) to 2 and (29) to 3
[(13)4(17)2(29)3]

(possible answers: 9 or 7 or 5 or 3 or 1)

lots of thanks for your answer!
robin!

Hi Robin,

The key to this problem is to observe that the units digit of 13⁴ is the same as the units digit of 3⁴. Do you see why? Similarly the units digit of 17² is the same as the units digit of 7², and the units digit of 29³ is the same as the units digit of 9³. Multiply the three resulting units digits read off the units digit of the product.

Penny

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