List any 3 numbers. It is always possible to find a subset of
adjacent numbers that add up to a multiple of 3. Can you explain
why and prove it?
How to build your own magic squares.
Weekly Problem 2 - 2013
After performing some operations, what number is your answer always a multiple of?
Think of any whole number. Double it and add five. Double this answer and add two. Now take away the number you first thought of. Which whole number will your final answer always be a multiple of?
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
This problem is taken from the UKMT Mathematical Challenges.View the archive of all weekly problems grouped by curriculum topic