checking procedure

In mathematics, a way of making quick checks on the answers to calculations. There are several methods, such as rounding the calculation to make an estimate. The most appropriate to use will depend on the type of calculation being done – algebraic equations may be checked by introducing the solution to see whether the equation works.

Common checking procedures include:

Reworking the calculation can be re-done in full

Rounding and estimation the numbers in the calculation can be rounded and an estimate produced

Use of inverses inverses can be used. For example:

59 × 17 = 1,003 and 1,003 ÷ 17 = 59

48 − 19 = 29 and 29 + 19 = 48

Placing the solution in an equation in algebra, when solving an equation, the solution can be put back into the equation to make sure that it works. For example:

2x + 6 = 28, giving 2x = 22, therefore x = 11; so, 2 × 11 + 6 = 28

Reasoning common sense will often help to decide whether an answer is sensible or not. For example, the order of magnitude of an answer can be checked to ensure that it is correct for the question.