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November 26, 2015
Posted by **Gilbert** on Wednesday, November 28, 2012 at 11:56am.

- Calculus -
**Steve**, Wednesday, November 28, 2012 at 12:14pmnote that the sum of the first n odd numbers is n^2

1=1

1+3=4

1+3+5=9

...

There are 50 odds below 100

There are 100 odds below 200

sum of 1st 50 odds is 50^2

sum of 1st 100 odds is 100^2

sum of odds between 100 and 200 is thus 100^2-50^2 = 7500