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Stage 4 of 20

Subtraction With Borrowing

Borrowing (or regrouping) lets you subtract larger digits from smaller ones by trading one ten for ten ones. This is essential for all multi-digit subtraction.

What You'll Learn

  • Recognize when borrowing is needed
  • Trade one ten for ten ones mentally
  • Complete facts like 13 − 8 without paper

Explanation

Consider 13 − 8. You cannot take 8 from 3, so borrow: 13 becomes 10 + 3, and you subtract 8 from 13 directly to get 5.

Another approach: count up from 8 to 13. Steps: 8→10 (2), 10→13 (3), total 5. This "add-up" method avoids borrowing entirely.

For single-digit problems disguised as teen numbers, memorize key facts: 11−5=6, 12−7=5, 13−8=5, 14−9=5.

Borrowing is a temporary trade. You give back the ten after using its ones — the total value never changes.

Pro Tips

  • • The "add-up" method is often faster than borrowing for mental math.
  • • Memorize subtraction from teens: 15−7, 16−9, 17−8 are high-frequency facts.
  • • Check your answer by adding back: 5 + 8 = 13 confirms 13 − 8 = 5.

Practice Exercises

Work through each problem mentally. Click "Show Answer" when you're ready to check.

  1. 1. 13 − 8 = ?
  2. 2. 12 − 7 = ?
  3. 3. 15 − 9 = ?
  4. 4. 14 − 6 = ?
  5. 5. 11 − 5 = ?
  6. 6. 16 − 9 = ?
  7. 7. 13 − 5 = ?
  8. 8. 15 − 7 = ?
  9. 9. 17 − 8 = ?
  10. 10. 14 − 9 = ?