A number is rational if we can write it as a fraction where the top number of the fraction and bottom number are both whole numbers. e.g. 1/2
An irrational number is any number which can't be written as a fraction. For example, PI (π) and the square root of two (√2) cannot be expressed as a fraction of two whole numbers, so they are both irrational. We will explore irrational numbers, square roots and PI in future skills.