Arrange the numbers 1 to 16 into a 4 by 4 array. Choose a number.
Cross out the numbers on the same row and column. Repeat this
process. Add up you four numbers. Why do they always add up to 34?
Stage: 3 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. More information on many of our other activities
can be found here.