Method C - Expanded Form Method
CPD: A Compendium of Mathematical Methods (By Jo Morgan), topic 2.1.3
Expanded Form Method: 753 − 491
This method is identical to the Decomposition Method (Method A) except we show the decomposition much more clearly.
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Step 1
- Write out the subtrahend and the minuend as a sum of their hundreds, tens and ones.
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Step 2
- Now set them out in columns.
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Step 3
- Start at the right. Subtract 1 from 3.
- Write the difference at the bottom, in the ones column.
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Step 4
- Now we want to subtract 90 from 50. To do this without using negatives, we can exchange.
- Instead of writing 750 as 700 + 50, we write it as 600 + 150.
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Step 5
- Now we can subtract 90 from 150.
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Step 6
- And subtract 400 from 600.
Step 7
- The difference is the sum of the numbers in the bottom row.
- 200 + 60 + 2 = 262.
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