St. Cronans Hub V9.0 June 2016


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Subtraction

Tips for Parents

There are many different ways to subtract one number from another. In St. Cronans BNS, all classes are taught to subtract in the same way, using the same words and phrases. This helps the boys understand subtraction and it avoids confusion.

When you are helping your son with his subtraction homework, it is important to:-

  • Use the words and phrases as used in class
  • Work out the subtraction sum the same way as it is done in class


This will help your son understand what he has learnt in school.

Remember this might be different from what you learnt in school!

These are the words we use:-




This is how we say our Subtraction Tables

"4 take away 4 is 0"
"5 take away 4 is 1"...

"9 take away 5 is 4"
"10 take away 5 is 5"...

"9 take away 3 is 6"
"10 take away 6 is 4"....


Test Subtraction Tables by asking:-

"12 take away 4 is?"
"5 take away 4 is?"....

Make sure to mix up the order you ask the tables to be sure your son really does know them.


This is how we read a Subtraction Sum



Read from
Left to Right

Say
"5 take away 4 is 1" or
you can say
"5 take away 4 equals 1"



This is how we work on Subtraction Sums


To make this sum easier to work on, we rewrite it as

When writing down a sum, remember to put
a
U over the Units (1s)
a
T over the Tens (10s) and for big sums
a
H over the Hundreds (100s)




Subtraction Sum 1 - This is a simple subtraction sum.

Click on the sum to see how it is done.


This is how you work out this sum

Step 1. Start at the top unit, 7 take away 2 is 5
Step 2. Go to the ten side, 3 take away 1 is 2

My answer is 25

Try it for yourself!


Subtraction Sum 2 - To do this subtraction sum you must regroup.

Click on the sum to see how it is done.


This is how you work out this sum

Step 1. Start at the top unit, 7 take away 8, I cannot do
Step 2. I must regroup and take a "ten" from 3, change it to 2
Step 3. Bring the "ten'" beside the 7, now I have 17
Step 4.
17 take away 8 is 9
Step 5. Go to the ten side, 2 take away 1 is 1

My answer is 19

Try it for yourself!


Go to our Maths - Subtraction Page for online activites to help your child with subtraction.

Subtraction Tables - Try Maths Magican and Maths Mayhem

Subtraction Practise - Try NLVM - enter your own sums.

Play the subtraction games to improve subtracting skills.

Talk to your son's teacher about any difficulties your son is having with his school work.


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