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What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?

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ABC

In the multiplication calculation, some of the digits have been replaced by letters and others by asterisks. Can you reconstruct the original multiplication?

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Oddly

Find the sum of all three-digit numbers each of whose digits is odd.

Number Detective

Stage: 2 Challenge Level: Challenge Level:1

Calling all detectives! You will need to think creatively, use your reasoning skills and your problem solving strategies 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 ones place.
  • The 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.


You might now like to play the game Statement Snap or have a go at Satisfying 4 Statements.

The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice. More information on many of our other activities can be found here.
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NRICH is part of the family of activities in the Millennium Mathematics Project.