### Odd Differences

The diagram illustrates the formula: 1 + 3 + 5 + ... + (2n - 1) = nÂ² Use the diagram to show that any odd number is the difference of two squares.

### Triangular Triples

Show that 8778, 10296 and 13530 are three triangular numbers and that they form a Pythagorean triple.

# Square Sum

##### Age 14 to 16 ShortChallenge Level

sum = 9$\times$ middle number
114$\times$9
124$\times$9
134$\times$9
144$\times$9 = 12$^2\times$3$^2$ = (12$\times$3)$^2$ so is a square number