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Threes and Fours

Age 14 to 16 Short
Challenge Level

Answer: 3444

Digits add up to a multiple of 3
3 + 4 = 7 (at least one of each)
Adding more 3s will not help get closer to a multiple of 3
3 + 4 + 4 = 11
3 + 4 + 4 + 4 = 15

Smallest possibility: 3444
44 is divisible by 4 so 3444 is divisible by 4

This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.
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.
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