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  • Jarrow Cross C of E Primary School
‘Living and Learning’
Value in Everyone

Wednesday 3rd February

Today's learning will focus on checking strategies. 


What is a strategy

A strategy is a method you can use to work something out.


Once we have found an answer, we can always check it by using the inverse operation. Equally, you might get questions that require you to use the inverse operation to work out missing numbers. 


What is the inverse operation

Opposite operations that undo each other. Addition and subtraction are inverse operations. Multiplication and division are inverse operations.


For example: 


If we calculated 5,345 + 2, 452 = 7, 797,
to check we got the answer correct we can also calculate 7,797 - 5,345 which should equal to 2,452 and if it doesn't it could mean that an error has been made.


Another example:

In a test, you could get a question like this:    ? -   8,542  = 3,214

In order to work out the missing number/ value, you must carry out the inverse operation:
8, 542 + 3,214 = 11, 756 

Therefore 11,756 - 8,542 = 3,214.


To summarise, if you only get part of a calculation that involves the final answer and part of the calculation, you MUST carry out the inverse operation (the opposite calculation to what it is asking. 


You MUST Watch this video to help explain this further and to support your child with the layout and structure of the questions:  Aut4.7.4 - Checking strategies on Vimeo


Now, download and complete the worksheet below.