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'Number Detective' printed from http://nrich.maths.org/

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Follow the clues to find the mystery number from the list below.

Inspector with magnifying glass.

  • The number has two digits.
  • Both of the digits are even.
  • The digit in the tens place is greater that the digit in the unit (or ones) place.
  • The units (or ones digit) is not in the three times table.
  • The tens digit is not double the ones digit.
  • The sum of the two digits is a multiple of five.

18 & 86, 120 & 42, 46 & 64, 80 & 8, 22 & 83.