You may also like

problem icon

Old Nuts

In turn 4 people throw away three nuts from a pile and hide a quarter of the remainder finally leaving a multiple of 4 nuts. How many nuts were at the start?

problem icon

Mod 7

Find the remainder when 3^{2001} is divided by 7.

problem icon

Prime AP

What can you say about the common difference of an AP where every term is prime?

Purr-fection

Stage: 5 Challenge Level: Challenge Level:1

What is the smallest perfect square that ends with the four digits 9009?

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.
Copyright © 1997 - 2017. University of Cambridge. All rights reserved.
NRICH is part of the family of activities in the Millennium Mathematics Project.