Showing posts with label adding long stretches of numbers. Show all posts
Showing posts with label adding long stretches of numbers. Show all posts

Tuesday, March 26, 2013

Skipping over the busy-work

Many people know this math problem, but I'm going to post it here anyway, because I've always liked the solution.
Add numbers 1 through 100.
Of course, you could just go through and add...
1+2=3
3+3=6
6+4=10
10+5=15*
... but that would be a lot of busy-work, and mathematicians don't approve of busy-work. 
*One small cool thing about the sequence you get from going through and adding everything (1, 3, 6, 10, 15, 21, 28...): these are the triangular numbers

So how can you do this in a much faster, easier, and more effective way?

To find the answer, go to answersdiscarded.blogspot.com. As usual, this is where I beg you to try to figure it out by yourselves before checking the answer.

If you've already done that problem, do this one:
Add all numbers divisible by three from 100 to 200.