Squares and Odd Numbers

Add up odd numbers from 1 onwards and you get square numbers!

Like this:

Odd
Number
Running
Total
 
11= 1 × 1
34= 2 × 2
59= 3 ×3
716= 4 × 4
925= 5 × 5
1136= 6 × 6
etc...

Is this some kind of magic?

odd square numbers

Not really, just look at this picture:

It is good to know this, as it may help you solve things one day.

There are more such tricks, see Partial Sums.