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Old 07-31-2007   #1
ViVI
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Default Hii :] People who like math...help me pleassssse! Ty?

The digital root of a number is found by adding all the digits of the number and of that result, and so on until a single digit is obtained. The digital root of 759 is 3 because 7 + 5 + 9 = 21 and 2 + 1 = 3. The digital root of 813,520 is 1 because 8 + 1 + 3 + 5 + 2 + 0 = 19, 1 + 9 = 10, and 1 + 0 - 1. If a number is the square of a positive integer, find the numbers that are possible digital roots.
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Old 07-31-2007   #2
huckleberry
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Isn't school over for the year?
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Old 07-31-2007   #3
dutch_prof
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Hmm, interesting question.The digital root of a number is equivalent to the original number modulo 9.The digital root of N^2 depends only on the digital root of N. We list all possible situations, where d(...) stands for the digital root:d(1^2) = d(1) = 1d(2^2) = d(4) = 4d(3^2) = d(9) = 9d(4^2) = d(16) = 7d(5^2) = d(25) = 7d(6^2) = d(36) = 9d(7^2) = d(49) = 4d(8^2) = d(64) = 1d(9^2) = d(81) = 9The possible values are: 1, 4, 7 and 9.
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