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Detailed Explanation of Subtracting a One-Digit Number from a Two-Digit Number with Regrouping ➖

When you subtract a one-digit number from a two-digit number, sometimes the number in the ones place is smaller than the number you want to take away. This means you need to use regrouping (also called borrowing) to help you subtract. Let’s learn how to do this step-by-step! This skill is part of Year 2 Maths in the UK National Curriculum.

What is Regrouping? 🔄

Regrouping means changing one ten into ten ones so it is easier to subtract when the ones are too small.

Step-by-Step Method 📝

  1. Look at the two-digit number: For example, 42.
  2. Look at the one-digit number you want to subtract: For example, 7.
  3. Check the ones place: In 42, the ones place is 2. Can you take away 7 from 2? No, because 2 is smaller than 7.
  4. Regroup from the tens place: Take 1 ten (which is 10 ones) from the 4 tens.
    • Now the 4 tens become 3 tens.
    • Add the 10 ones to the 2 ones you already have: 10 + 2 = 12.
  5. Subtract the ones: Now subtract 7 from 12. 12 – 7 = 5.
  6. Subtract the tens: After regrouping, you have 3 tens left. No tens are subtracted, so it is 3 tens = 30.
  7. Put the answer together: Tens (30) + Ones (5) = 35.

So, 42 – 7 = 35.

Another Example 🔢

Subtract 15 – 8.

  • Tens digit is 1 and ones digit is 5.
  • 5 is smaller than 8. So, take 1 ten from tens (1 ten becomes 0 tens).
  • Add 10 ones to the 5 ones: 10 + 5 = 15.
  • Subtract 8 from 15 = 7.
  • Tens left = 0, so answer = 7.

Answer: 15 – 8 = 7.

Tips to Remember 💡

  • Always check the ones place first.
  • If the ones digit is smaller, regroup by borrowing 1 ten.
  • Change one ten into 10 ones.
  • Subtract the ones, then subtract the tens.
  • Write your answer with the tens on the left and ones on the right.

How Does This Fit in the National Curriculum? 🎓

In Year 2 Maths, students learn to subtract numbers using concrete objects, pictures, and number lines. Regrouping is important so children develop a clear understanding of place value and how to subtract numbers that need exchanging tens for ones. This helps build strong mental math and problem-solving skills.

Keep practising subtracting with regrouping – it will help you become quicker and more confident! 🚀

20 Examination-Style Questions with Answers on Subtracting a One-Digit Number from a Two-Digit Number with Regrouping 🧮

Here are 20 questions to practice subtracting a one-digit number from a two-digit number with regrouping. These follow the Year 2 curriculum for Key Stage 1 maths and help you get better at taking away smaller numbers from bigger numbers where you need to regroup (borrow from the tens).

Questions ❓

  1. 31 − 8 =
  2. 42 − 9 =
  3. 54 − 7 =
  4. 63 − 5 =
  5. 71 − 6 =
  6. 85 − 8 =
  7. 92 − 7 =
  8. 73 − 9 =
  9. 64 − 6 =
  10. 81 − 7 =
  11. 53 − 8 =
  12. 67 − 9 =
  13. 74 − 7 =
  14. 60 − 8 =
  15. 88 − 9 =
  16. 79 − 6 =
  17. 95 − 8 =
  18. 62 − 7 =
  19. 70 − 9 =
  20. 84 − 7 =

Answers ✔️

  1. 31 − 8 = 23
  2. 42 − 9 = 33
  3. 54 − 7 = 47
  4. 63 − 5 = 58
  5. 71 − 6 = 65
  6. 85 − 8 = 77
  7. 92 − 7 = 85
  8. 73 − 9 = 64
  9. 64 − 6 = 58
  10. 81 − 7 = 74
  11. 53 − 8 = 45
  12. 67 − 9 = 58
  13. 74 − 7 = 67
  14. 60 − 8 = 52
  15. 88 − 9 = 79
  16. 79 − 6 = 73
  17. 95 − 8 = 87
  18. 62 − 7 = 55
  19. 70 − 9 = 61
  20. 84 − 7 = 77

How to Solve These 🧠

Remember when you subtract a one-digit number from a two-digit number and the ones number is too small, you need to regroup. This means you take 1 ten from the tens place so you have more ones to take away from.

For example, in 42 − 9:

  • Look at the ones: 2 − 9 is tricky because 2 is smaller.
  • Borrow 1 ten from the 4 (tens), so you now have 3 tens.
  • Add 10 ones to 2 ones, now you have 12 − 9 = 3 ones.
  • Tens: 3 − 0 = 3 tens.
  • So the answer is 33.

Keep practising these to get super confident in subtracting numbers with regrouping! 👍

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