I've been reading about a form of alternative education (here) recently, and been thinking about the need for creativity (research) in my daily work. I've also been reading about approaches to thinking, and creative thinking.
I saw an example of creative thinking recently to add quickly the numbers 1 to 10, or 1 to 100. The method was quick but not necessarily intuitive - which is part of the point.
I started thinking about this to see if I could adapt the method to add the even numbers between say 1 and 300. I did the mental arithmetic fairly quickly and then checked my working with pen and paper afterwards.
There have been some interesting tester challenges doing the rounds recently, and I thought that a thinking challenge was in order.
So, the challenge is to add the even numbers (2, 4, 6,...) from 1 to 300.
Bonus points if you can do it in less than 30 seconds! Less than 10 seconds if using a calculator. (I'm not counting alternative thinking time here - that I'll leave to you to work on.)
If you want to post a comment with the answer here then you'll need to show your thinking!
(I'll delay comment publication a few days in case there's any latecomers that wants to try it - without being tempted by the comments.)
There will be a follow-up post - where I identify the book and some other things I've learnt from it.