# math

What is the sum of all two digit positive integers whose squares
end with the digits 01?

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1. the only number whose square ends in a 1 is a number that ends in 9 or 1

so a quick check on my trusty calculator and squaring numbers like 11,21,31,..91,19,29,39,..99

showed me
51^2 = 2601
49^2 = 2401.
99^2 = 9801

the sum of these 3 is 199

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posted by Reiny

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