# Recognising and using the inverse relationship between addition and subtraction and use this to check calculations and solve missing number problems.

### Let's practice with concrete manipulatives

Start with this example when tackling the problem. Use any manipulatives you have in hand. Talk about the inverse relationship between addition and subtraction. 3+4 =7 4+3=7 7-3=4 7-4=3 Practice by giving your child one sum for example 5+4=9 and counters. Try to arrange them in different ways. Say “let’s mix them up and check if they still make sense”.

When this is understood. Write few sums with missing numbers:

_+ 5=9

_- 4=5

### Let's use a number line - addition

Count first in 10s to get as close to the desired number as possible. When you can't add ten (because you will go over the number that you suppose to stop on)- count in ones untill you get to your number. Finnaly count how many tens and ones did you use and you have your answer. I do recommend to double check the answer using column method.

Have a go!

### Let's use a number line - subtraction and inverse relationship

Count BACK: first in 10s to get as close to the desired number as possible. When you can't take away another ten - count in ones untill you get to your number. Finnaly count how many tens and ones did you use and you have your answer. I do recommend to double check the answer using column method. Have a go!

### KS1 Problem Solving Book 1

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### KS1 Problem Solving Book 2

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### KS1 Problem Solving Book 3

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### Mental Maths 1

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### Mental Maths 2

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