NB TCN Numeracy key terms

The value a digit has because of its position in a number; in 4,706 the 7 means seven hundreds, while in 7,046 it means seven thousands.

A number written in ordinary digits with each digit in its correct place, such as 3,052 rather than three thousand fifty-two written in words.

A number broken into the sum of its place values, for example 3,052 written as 3,000 + 50 + 2, which makes each digit's contribution visible.

Replacing a number with a nearby value of a chosen place, decided by the next digit: 5 or more rounds up, 4 or less keeps the digit unchanged.

Finding an approximate answer by rounding or simplifying numbers first, useful for checking whether an exact calculation is reasonable in size.

The agreed sequence for evaluating expressions: brackets first, then powers, then multiplication and division left to right, then addition and subtraction left to right.

Multiplying a sum by a number gives the same result as multiplying each part separately and adding, so 6 x 24 equals 6 x 20 plus 6 x 4.

An operation that undoes another, such as addition undoing subtraction or multiplication undoing division; used to solve equations and check answers.

A whole number that divides another exactly with no remainder; 1, 2, 3, 4, 6 and 12 are all factors of 12.

The result of multiplying a number by a whole number; the multiples of 4 include 4, 8, 12 and 16, and they continue without end.

A whole number greater than 1 with exactly two factors, itself and 1; 2, 3, 5, 7 and 11 are prime, while 1 and 9 are not.

The smallest number that is a multiple of two or more given numbers; for 6 and 8 the least common multiple is 24.

The largest whole number dividing two or more given numbers exactly; for 18 and 24 the greatest common factor is 6.

Fractions with the same value written with different numbers, produced by multiplying or dividing numerator and denominator by the same amount, as 2/3 equals 4/6.

Rewriting a fraction with the smallest possible whole-number numerator and denominator while keeping the same value, by dividing out common factors.

The bottom number of a fraction, showing how many equal parts the whole is divided into; in 3/8 the denominator is 8.

The top number of a fraction, showing how many of the equal parts are being counted; in 3/8 the numerator is 3.

A fraction whose numerator is equal to or larger than its denominator, such as 7/4, meaning a value of one or more wholes.

A value written as a whole number plus a fraction, such as 1 3/4; it can be rewritten as the improper fraction 7/4.

A position to the right of the decimal point naming a fraction of ten; the first place is tenths, the second hundredths, the third thousandths.

A comparison to 100, meaning per hundred; 35 percent equals 35/100 or 0.35, and it describes a part of a whole.

The size of an increase or decrease expressed as a percent of the original amount, found by dividing the change by the original and multiplying by 100.

The starting value before a percent increase or decrease is applied; it is the base used as the denominator when calculating percentage change.

A comparison of two or more quantities by division, often written 3:5 or 3 to 5, stating how much of one quantity there is per unit of another.

A statement that two ratios are equal, such as 3/4 = 9/12; solving one usually means finding an unknown value in the matching ratio.

A method for solving a proportion by multiplying the numerator of each fraction by the denominator of the other and setting the two products equal.

A rate expressed per single unit of the second quantity, found by dividing; for example 150 kilometres in 3 hours gives 50 kilometres per hour.

The fixed relationship between a drawing or model and the real object, such as 1 centimetre on a map standing for 5 kilometres on the ground.

A word part attached to a base unit to show a power of ten, such as kilo for one thousand, centi for one hundredth, and milli for one thousandth.

The fundamental unit a prefix is attached to, such as metre for length, gram for mass, or litre for capacity in the metric system.

Changing a measurement into a different unit without changing the quantity, by multiplying by a conversion factor equal to one, such as 100 centimetres per metre.

The total distance around the outside of a flat shape, found by adding the lengths of all its sides.

The amount of flat surface a shape covers, measured in square units; a rectangle's area is length multiplied by width.

The amount of space a solid occupies, measured in cubic units; a rectangular box's volume is length times width times height.

The amount a container can hold, usually measured in litres or millilitres, and often confused with the volume of the container's material.

The average found by adding all values and dividing by how many there are; it is affected strongly by unusually high or low values.

The middle value when data are arranged in order; with an even count it is the mean of the two middle values, and outliers barely affect it.

A simple measure of spread found by subtracting the smallest value in a data set from the largest value.

A mathematical statement that two expressions are equal, often containing an unknown letter whose value makes the statement true.

A sequence in which each term changes by the same fixed amount, so plotting the terms against their positions gives a straight line.