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A prime number less than 100 is selected randomly. What is the probability that its square has units digit 7?

waffles  Apr 28, 2017
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There is no possibility.......the prime will end either in 1, 3, 7 or 9

 

And the square of any number ending  in those digits will have a unit number of either 1 or 9

 

 

cool cool cool

CPhill  Apr 28, 2017

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