Numerical skills

Surds are square roots which can’t be reduced to rational numbers. Some can be simplified using various rules or by rationalising the denominator.

Indices show where a number has been multiplied by itself, eg squared or cubed, or to show roots of numbers, eg square root. Some terms with indices can be simplified using the laws of indices.

Numbers can be rounded to significant figures. Numbers which are significant are usually non-zero numbers. Zeros can become significant however under two conditions.

You can calculate the original amount from before a percentage rise/fall by reversing the change.

Appreciation, depreciation and compound interest can all be calculated using the multiplier method.

Adding, subtracting, multiplying and dividing can be applied to mixed number fractions. Each has its own method that helps make sure the numerator and denominator are treated correctly.