Copyright © University of Cambridge. All rights reserved.
'Mystery Matrix' printed from http://nrich.maths.org/
Have a look at this table square or matrix:
Can you see how it has been constructed?
Why are some numbers in black and some in red?
Can you explain why the red $6$ is in that particular square?
Why is there a $45$ in the bottom right-hand corner?
You will notice that the numbers $2$ - $9$ are used to generate the matrix and only one of these numbers is used twice (the $2$).
Can you fill in the matrix (table square) below?
The numbers $2$ -$12$ were used to generate it with, again, just one number used twice.
Click here for a poster of this problem.