Maths

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This mystery number has 3 digits.Its digits are in the descending order. The hundreds' digit is two more than the ones' digit. If you add the 3 digit it gives you a dozen. Guess this mystery number?

  • Maths -

    If the digits are in strict descending order, then they must be [n+1]n[n-1], the sum of which is 12, i.e.
    n+1 + n + n-1 = 12
    Solve for n.

  • Maths -

    The hundred digit is two more than the ones.
    If you add three it will be 12.
    Which means the hundreds is 12-3=9
    To find the ones 9 - 2=7
    Now we found 9_7.
    To finish for sure the decending means 8
    So the answer is 987.

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