Basic Math Definitions

We have collected some basic definitions on this page.
For lots more definitions, explanations, etc, use search above.
 
Or look up your word in the:
Illustrated Mathematics Dictionary
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The Basic Operations

In basic mathematics there are many ways of saying the same thing:

Symbol
Words Used
+
Addition, Add, Sum, Plus, Increase, Total
Subtraction, Subtract, Minus, Less, Difference, Decrease, Take Away, Deduct
×
Multiplication, Multiply, Product, By, Times, Lots Of
÷
Division, Divide, Quotient, Goes Into, How Many Times

Addition is ...

... bringing two or more numbers (or things) together to make a new total.

The numbers to be added together are called the "Addends":

addition

Subtraction is ...

... taking one number away from another.

Minuend - Subtrahend = Difference

Minuend − Subtrahend = Difference

Minuend: The number that is to be subtracted from.
Subtrahend: The number that is to be subtracted.
Difference: The result of subtracting one number from another.

Multiplication is ...

... (in its simplest form) repeated addition.

Here we see that 6+6+6 (three 6s) make 18:

multiplication

It can also be said that 3+3+3+3+3+3 (six 3s) make 18

But we can also multiply by fractions or decimals, which goes beyond the simple idea of repeated addition:

Example: 3.5 × 5 = 17.5

which is 3.5 lots of 5, or 5 lots of 3.5

Division is ...

... splitting into equal parts or groups. It is the result of "fair sharing".

Division has its own special words to remember.

Let's take the simple question of dividing 22 by 5. The answer is 4, with 2 left over. Here we see the important words:


Which is the same as:

A Fraction is ...

... part of a whole.

A fraction is written with the bottom part (the denominator) telling us how many parts the whole is divided into,

and the top part (the numerator) telling us how many parts we have.

See Fractions for more details.

A Decimal Number is ...

... a number that contains a Decimal Point.

decimal number

See Decimals for more details.

A Percentage is ...

... parts per 100. The symbol is %

q

Example: 25% means 25 per 100 (25% of this box is green)

See Percentages for more details.

Average (Mean) is ...

... the sum divided by the count.

We calculate the average by adding up all the values, then divide by how many values.

Example: What is the average of 9, 2, 12 and 5?

Add up all the values: 9 + 2 + 12 + 5 = 28

Divide by how many values (there are four of them): 28 ÷ 4 = 7

So the average is 7

See Mean for more details.