written methods of subtraction

More subtraction using the standard method

I have had several requests for another page of subtracting 2-digits from 3-digits, a worksheet that was published about a month ago. So here it is!

The benefit of the worksheet is that the questions keep to fairly small numbers but increase in difficulty and can show clearly whether children have fully grasped the standard method or whether they need more practice.

The last three questions aer especially tricky and if children are getting these correct it would suggest that they have really understood the concepts.

If these are set as homework make it very clear that all working out needs to be shown (e.g. hundreds crossed out and made one smaller and adjusting 10 tens etc). Of course I see no reason why children should not use a calculator to see if they are correct and if incorrect to try and work out where they have gone wrong.

Standard subtraction of 2-digits from 3-digits (2)

Written methods of subtraction

During the early years children are not expected to employ written methods to subtract numbers. The aim at this stage is to use mental methods and become really efficient with this. However, the time comes when they must be taught one efficient method of subtraction.

There are three essential skills children should have before embarking on the standard written method:

a. know, off by heart, all addition and subtraction facts to 20

b. be able to subtract multiples of 10 (such as 150 – 60)

c. partition 2-digit and 3-digit numbers into multiples of one hundred, ten and one in different ways (For example partition 83 into 80 and 3 or 70 and 13).

When these skills have been securely grasped it is time to move towards the standard method, which is usually known as decomposition. We have a number of worksheets which explain this method and give practice with it. They can be found in our Four Rules section under subtraction.

Go to our written subtraction worksheets

Free maths worksheets: standard written methods of subtraction

Standard written methods of subtraction worksheets from mathsblog.co.uk

Written methods of subtraction often cause problems for children and it is important to state that a good mental knowledge of numbers is essential if written methods are going to be grasped successfully.

In the UK the standard method of subtraction is often known as decomposition. It should be used when numbers are too large or too awkward to subtract mentally. Remember: mental methods should be the first resort!

The first page of the link shows how the decomposition method works, and is probably the one you learnt at school, although there are other, equally valid methods of subtraction.

Standard written subtraction 1