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REVERSABILITY: Step 4 Go back to the subtraction problem and write in he answer. 45 – 27 =

REVERSABILITY Reversibility is when you turn a SUBTRACTION problem into an ADDITION problem to find the answer A step by step process and how it is to be set out in your books follows.

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REVERSABILITY: Step 4 Go back to the subtraction problem and write in he answer. 45 – 27 =

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  1. REVERSABILITYReversibility is when you turn a SUBTRACTION problem into an ADDITION problem to find the answerA step by step process and how it is to be set out in your books follows.

  2. REVERSABILITYSarah had 45 apples but gave 27 of them to her friends and neighbours. How many did she have left then?45 – 27 =

  3. REVERSABILITY: Step 1Turn the subtraction problem into an addition problem. *Move the second number to the front *Put in a plus sign in instead of a subtraction*Leave a space for the missing number*Put in an equals sign* Write in the answerSo in short:45 – 27 =becomes27 + = 45

  4. REVERSABILITY: Step 2Now all you have to do is solve27 + = 45 and you will have your answerfor 45 – 27 =

  5. REVERSABILITY: Step 3Work out how much you need to get from 27 to 45. Use tidy numbers. For example to get from 27 to 30 is 3,then 30 to 45 is 15. Add 3 and 15 and you have 18! That’s your answer.27 + 3 (30) +15 = 453 +15 = 1827 + = 45 18

  6. REVERSABILITY: Step 4Go back to the subtraction problem and write in he answer.45 – 27 = 18

  7. This is how I want to see this strategy set out in you exercise book.1. 45 – 27 = ? 27 + ? = 45 27 + 18 = 45 45 -27 = 182. 78 – 45 = ? 45 + ? = 78 45 + 32 = 78 78 – 45 = 32

  8. Stage 553 – 26 = ?26 + ? = 5326 + 27 = 5353 – 27 = 26

  9. Stage 6553 – 226 = ?226 + ? = 55326 + 327 = 5353 – 27 = 326

  10. Stage 65.53 – 2.26 = ?2.26 + ? = 5.532.26 + 3.27 = 5.535.53 – 2.26 = 3.27

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