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Subtraction

Taking numbers away

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Taking Numbers Away

Key Points

  • Subtraction means taking one number away from another
  • The answer to a subtraction problem is called the DIFFERENCE
  • Subtracting 0 from any number doesn't change it (e.g., 8 - 0 = 8)
  • You can check subtraction by adding back: if 9-4=5, then 5+4=9 ✓

📘 Examples

❓ 10 - 4 = ?

✅ Start at 10, count back 4: 9, 8, 7, 6. Answer: 6!

❓ 45 - 22 = ?

✅ Subtract ones: 5-2=3. Subtract tens: 4-2=2. So 45-22 = 23!

❓ Sara has 9 stickers and gives away 3. How many left?

✅ 9 - 3 = 6 stickers!

🌟 Fun Fact!

Subtraction is just addition in reverse! If you know 3+4=7, you also know 7-4=3! 🔄

About Elementary Learning Platform

Subtraction causes more difficulty than addition, partly because it has several distinct meanings. Taking away, finding a difference, and working out how many more are needed are all subtraction, and children who only meet the first are often stuck by the others.

Understanding subtraction as the inverse of addition is the idea that eventually makes it straightforward, because it lets a child use facts they already know.

How to practise at home

  • Ask how many more rather than only take away, so both meanings of subtraction become familiar.
  • Use money. Working out change is subtraction with an obvious purpose and immediate feedback.
  • Link each subtraction to its addition fact: if 7 + 5 = 12 then 12 - 5 = 7. This halves what has to be memorised.
  • Use a number line for differences, counting up from the smaller number to the larger.

Common mistakes to watch for

  • Subtracting the smaller digit from the larger in each column regardless of position, so 52 - 27 becomes 35 instead of 25.
  • Forgetting to reduce the next column after borrowing.
  • Treating subtraction as commutative and assuming 3 - 8 is the same as 8 - 3.
  • Struggling with zeros when borrowing across them, as in 300 - 47.

Frequently asked questions

Why do children find subtraction harder than addition?

Because it has several meanings that look different: taking away, finding a difference, and finding how many more are needed. Children taught only take away are often confused by the other forms.

What is borrowing in subtraction?

Exchanging one unit from the next column when the digit you are subtracting from is too small, so a ten becomes ten ones. It is sometimes called regrouping, which describes what is happening more accurately.

How can I explain subtraction as the opposite of addition?

Use fact families. Showing that 4 + 6 = 10, 6 + 4 = 10, 10 - 4 = 6, and 10 - 6 = 4 all describe the same relationship makes the connection concrete.