Make a set of numbers that use all the digits from 1 to 9, once and
once only. Add them up. The result is divisible by 9. Add each of
the digits in the new number. What is their sum? Now try some other
possibilities for yourself!
Is there an efficient way to work out how many factors a large number has?
Age 11 to 14 Challenge Level
Find some triples of whole numbers $ a $, $ b $ and $ c $ such that
$ a^2 + b^2 + c^2 $ is a multiple of 4. Is it necessarily the case
that $ a $, $ b $ and $ c $ must all be even? If so, can you
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.