Copyright © University of Cambridge. All rights reserved.

'Alternating Sum' printed from https://nrich.maths.org/

Show menu


Given that the number 2008 is the correct answer to the calculation below, what is $n?$$$1-2+3-4+5-6+...+(n-2)-(n-1)+n$$

This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.