Maths Terms for 11-13 Yr Olds

1. A part to whole comparison. Example: Where £20 is shared between two people in the ratio 3:5, the first receives £7.50 which is 3/8 of the whole £20. This is his proportion of the whole.

2. If two variables x and y are related by an equation of the form y = kx, then y is directly proportional to x; it may also be said that y varies directly as x. When y is plotted against x this produces a straight line graph through the origin. If two variables x and y are related by an equation of the form y = then y is inversely proportional to x; it may be said that y varies inversely as x.

One of the four regions into which a plane is divided by the x and y axes in the Cartesian co-ordinate system.

Relating to a quantity or number. Used as an adjective to describe conclusions and explanations that use mostly numbers and equations as opposed to words (qualitative).

A part to part comparison. The ratio of a to b is usually written a : b.

Example: In a recipe for pastry fat and flour are mixed in the ratio 1 : 2 which means that the fat used has half the mass of the flour. The mixture is 1/3 fat, and 2/3 flour.

A number that is an integer or that can be expressed as a fraction whose numerator and denominator are integers, and whose denominator is not zero. 

Rational numbers, when expressed as decimals, are recurring decimals or finite (terminating) decimals. Numbers that are not rational are irrational. Irrational numbers include square roots and pi, which have infinite, non-recurring decimal places

A number that is rational or irrational. Real numbers are those generally used in mathematics, science and everyday contexts.

The multiplicative inverse of any non-zero number. Example: 1/3 is the reciprocal of 3. Any number multiplied by its reciprocal gives 1. Example 1/3 x 3 = 1. (Division by 0 is not defined and 0 has no reciprocal).

A decimal fraction with an infinitely repeating digit or group of digits. Example: The fraction 1/3 is the decimal 0.33333, referred to as nought point three recurring and may be written as 0.3 with a dot over the three. Where a block of numbers is repeated indefinitely, a dot is written over the first and last digit in the block.

A common property or connection between two or more variables. Example: in a linear graph of the form y = 2x, there is a linear relationship between x and y. For every x, y is half the size. Compare with 'correlation'.