Square numbers

A square number is a number multiplied by itself, for example 2x2, 7x7, even 100x100. Square numbers are written with a small number 2 in front of them like this: $$3^2$$

Below is a list of square numbers you will need to learn:
 * $$1^2 = 1$$
 * $$2^2 = 4$$
 * $$3^2 = 9$$
 * $$4^2 = 16$$
 * $$5^2 = 25$$
 * $$6^2 = 36$$
 * $$7^2 = 49$$
 * $$8^2 = 64$$
 * $$9^2 = 81$$
 * $$10^2 = 100$$
 * $$11^2 = 121$$
 * $$12^2 = 144$$
 * $$13^2 = 169$$
 * $$14^2 = 196$$
 * $$15^2 = 225$$
 * $$16^2 = 256$$

It's also handy to know that the difference between each square number increases by two each time, as you can see by looking closely at the square numbers in the list above.