How to add, subtract, multiply, divide decimals

Simon

12 years ago

How to add, subtract, multiply, divide decimals is an important foundational numeracy skill.

Learn these, practice them and always keep to the same methods!

There are 6 main numeracy skills that will help with your maths. Click here to read more.

Click here to visit addition skills , subtraction skills , division skills , fraction skills videos.

A decimal number is a number written in ‘base 10,’ and is generally used with money or measurements such as weight, area, distance etc. Working with decimals can be relatively straightforward, but you need to remember:

always keep the decimal point in the correct place
always keep the numbers in the same column
when calculating, work out the ‘numbers,’ then add the decimal point

Also, when you are learning how to add, subtract, multiply, divide decimals, try to work with fractions as an alternative – don’t forget that many are ‘interchangeable’ and it might be easier to calculate.

So:

Decimal	Is the same as this fraction..	Is the same as this percentage..
0.10	1/10	10%
0.25	1/4	25%
0.50	1/2	50%
0.75	3/4	75%
1.00	1 whole	100%

Sometimes calculations may also create a very long number and some questions ask for the answer to 2 decimal places or 3 significant figures. I’ll post about this very soon :-).

In the meantime, did you know:

The decimal system was developed in Ancient India and Arabia.
The earliest decimal system was probably invented by Elamites of Iran in the period 3500-2500 BC.
The decimal point we use was probably invented by Bartholomaeus Pitiscus in 1612.
A comma is used instead of a decimal point in some European countries.
The value of ‘pi’ has been calculated to 2.7 trillion decimal places – 3.14159 26535 89793 23846 26433 83279 50288 41971 69399 37510 are the first 50.

Adding decimals