How_To_Be_Good_At_Math

Glossary

Glossary

acute angle An angle that

is less than 90 degrees.

adjacent Next to each other,

such as two angles or sides

of a shape.

algebra The use of letters or

other symbols to stand for

unknown numbers when

making calculations.

angle A measure of the

amount of turn from one

direction to another. You

can also think of it as the

difference in direction

between two lines meeting

at a point. Angles are

measured in degrees.

See degree.

anticlockwise Going round

in the opposite direction to a

clock’s hands.

apex The tip or pointed top

of any shape.

arc A curved line that forms

a part of the circumference

of a circle.

area The amount of space

inside any 2D shape. Area is

measured in square units,

such as square metres.

associative law A law saying

that if you add, for example,

1 + 2 + 3, it doesn’t matter

whether you add the 1 + 2 first

or the 2 + 3 first. The law works

for addition and multiplication,

but not subtraction or division.

asymmetrical A shape with

no reflective or rotational

symmetry is asymmetrical.

average The typical or middle

value of a set of data. There

are different kinds of averages

• see mean, median, and
  mode.

axis (plural axes) (1) One of the

two main lines on a grid, used

to measure the position of

points, lines, and shapes. See

also x axis, y axis. (2) An axis

of symmetry is another name

for a line of symmetry.

bar chart A diagram showing

data as rectangular bars of

different lengths or heights.

base The bottom edge of a

shape, if you imagine it sitting

on a surface.

block graph A diagram

that shows data as stacks

of square blocks.

brackets Symbols such as ( )

and [ ], used to surround

numbers. They help show

you which calculations you

should do first.

capacity The amount of

space inside a container.

Carroll diagram A diagram

that is used to sort data into

different boxes.

Celsius scale A scale of

temperature. Water boils at

100 degrees on this scale.

centigrade scale Another

name for the Celsius scale.

chord A straight line that cuts

across a circle but doesn’t go

through the centre.

circumference The distance

all the way round the outside

of a circle.

clockwise Going round in

the same direction as a

clock’s hands.

common denominator

A term used when two or

more fractions have the same

lower number. See

denominator.

common factor A factor

that two or more numbers

share. See factor.

common multiple A number

that is a multiple of two or

more different numbers. For

example, 24 is a multiple of 3

as well as of 4, and so is a

common multiple of these

numbers. See multiple.

commutative law A law that

says that, for example, 1 + 2

is the same as 2 + 1, and the

order the numbers are in

doesn’t matter. It works for

addition and multiplication, but

not subtraction or division.

compass (1) An instrument

that shows the direction of

north, as well as other

directions. (2) A pair of

compasses is an instrument

used to draw circles and parts

of circles.

cone A 3D shape with a

circular base and a side that

narrows upwards to its apex.

See apex

congruent Geometrical

shapes that have the same

size and shape.

conversion factor A number

you multiply or divide by to

change a measurement from

one kind of unit to another. For

example, if you’ve measured a

length in metres and need to

know it in feet, you have to

multiply by 3.3.

coordinates Pairs of numbers

that describe the position of a

point, line, or shape on a grid

or the position of something

on a map.

cross section A new face

made by cutting a shape

parallel to one of its ends.

See face.

cube number When you

multiply a number by itself,

and then by itself again, the

result is called a cube number.

cubic unit Any unit, such

as a cubic centimetre, for

measuring the volume of

a 3D shape. See unit.

cuboid A box-like shape with

six faces, where opposite

faces are identical rectangles.

cylinder A 3D shape with two

identical circular ends joined

by one curved surface. A tin

can is an example.

data Any information that

has been collected and can

be compared.

decimal Relating to the

number 10 (and to tenths,

hundredths, and so on). A

decimal fraction (also called

a decimal) is written using a dot

called a decimal point. The

numbers to the right of the dot

are tenths, hundredths, and so

on. For example, a quarter (^1 ⁄ 4 )

as a decimal is 0.25, which

means 0 ones, 2 tenths, and

5 hundredths.

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