Parents Guide to Subtraction This Power Point Presentation will Show Parents the Language We Use When Teaching Children Subtraction Using Decomposition.

Organising numbers: We organise numbers in columns like this: H T U Hundreds Tens Units Only a single figure can go into each column.

Count up to 9 9 H T U The units column is now full. You can only put one digit in each column. To make 10 we need to move to the next column.

The Tens Column 30 H T U We have 3 in the tens column and nothing in the units column. The number is 30.

The Hundreds Column 300 H T U We have 3 in the hundreds column and nothing in the tens or the units column. The number is 300.

Understanding Hundreds Tens and Units 319 H T U The number 319 is: 3 hundreds 1 ten 9 units

How to Take Away Make sure the biggest number is on the top line

How to Take Away Begin in the Units column. Say: 5 take away 4 is 1 H T U H T U

How to Take Away Move to the Tens column. Say: 0 take away 2 You have nothing – so you can’t take away 2! We need to EXCHANGE. H T U H T U

How to Take Away: Exchanging You have to take 1 out of the hundreds column. H T U H T U X12 Now we have 2 hundreds and 10 tens! Remember: You are taking 100 out of the hundreds column. 100 is the same as 10 tens!

We Exchanged 1 Hundred for 10 Tens Now we say: 10 take away 2 is 8 H T U H T U X 1 2 Answer: 281 There is no digit below the 2 in the hundreds column so we say: 2 take away 0 is

Exchanging When the digit on the top line is smaller than the digit on the bottom line we say: ‘We need to exchange.’

One More Example H T U H T U

One More Example 7 is smaller than 9. You have to take 1 out of the tens column. H T U H T U X15 Now we have 17 units and 5 tens! Remember: You are taking 10 out of the tens column. So the 7 becomes 17.

One More Example Now we say: 5 take away 2 is 3. H T U H T U X Move to the hundreds column. Say: 5 take away 3 is 2. Answer: 238 2

We hope this powerpoint will help you to work with your child at home. Please ask in school if you have any questions regarding our approach to teaching maths. Click Below to Return to Our School Website.