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Repeaters
Choose any 3 digits and make a 6 digit number by repeating the 3 digits in the same order (e.g. 594594). Explain why whatever digits you choose the number will always be divisible by 7, 11 and 13.
Oh! Hidden Inside?
Find the number which has 8 divisors, such that the product of the divisors is 331776.
Skeleton
Amazing as it may seem the three fives remaining in the following `skeleton' are sufficient to reconstruct the entire long division sum.
Age 11 to 14 Challenge Level:
What is the remainder when $2^{164}$ is divided by 7?
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NRICH is part of the family of activities in the Millennium Mathematics Project.
NRICH is part of the family of activities in the Millennium Mathematics Project.