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ELI5 Yahaaa

What is left

What Does Taking Away Do?

Subtraction answers two different questions with the same operation.

1 Start with some2−Remove some3 See whatremains
Or: how far apart are these two numbers?

  1. Step 1 of 5

    The obvious meaning: remove some.

    SevenEat threeFour left

    You had seven biscuits, you ate three, you have four. Subtraction counts what survived.

  2. Step 2 of 5

    The second meaning: find the gap.

    Taking away−Something is removedFinding the difference Nothing is removed —you measure a gap

    How much taller is a 140 cm child than a 120 cm one? 140 − 120 = 20. Same operation, but nothing was taken away from anybody.

  3. Step 3 of 5

    It undoes adding.

    Start at 4+Add 3 — now 7−Subtract 3=Back to 4Undo

    If 4 + 3 = 7 then 7 − 3 = 4. Every addition fact hands you a subtraction fact for free.

  4. Step 4 of 5

    Order matters here.

    Adding+Order does not matterSubtracting−Order changeseverything

    7 − 3 is 4, but 3 − 7 is not. Unlike adding, you cannot swap the numbers around and expect the same answer.

  5. Step 5 of 5

    Going past zero gives negatives.

    1 Count down from320Pass throughzero3−Land on −4

    3 − 7 lands three steps below zero: −4. That is not nonsense — it is a temperature, a debt, or a floor below ground level.

    Shopkeepers counted change by adding up: 'that's 3, and 2 makes 5' — using addition to do the subtraction.

The short version

Subtraction either removes an amount or measures the gap between two numbers — same operation, two jobs.

Try it yourself

Count out 10 coins, take away 4, then work out how many more you would need to get back to 10. Same number, both ways.

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