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Math Help - Find 4 digit number

  1. #1
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    Find 4 digit number

    PROBLEM:
    Find all four-digit numbers which are a complete square and in which the first two digits are equal and the last two digits are also equal.
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  2. #2
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    Working mod 100 we have that 44 is the only possibility for x^2 to have two digits. Which means this number AB (where A,B are digits) must end in 44. This means B=2 or B=8. Thus, 12,...,92 and 18,...,98. But since it is 4 digits the only possible choices are 32,...,92 and 38,...,98 and these are easy to check.
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