Subtraction with Regrouping Notes & Questions | Class 4 Mathematics | Drishti OS

Subtraction with Regrouping

What you'll learn

Subtract 4-digit numbers by borrowing (regrouping) across ones, tens, hundreds and thousands.
Handle borrowing across zeros, e.g. 5,004 − 2,368.
Check a subtraction answer using addition.

Key concepts

Level 1 — What is regrouping?

Verbal: When a digit on top is smaller than the digit below it, we "borrow" 1 from the next place to the left. Borrowing turns 1 ten into 10 ones, 1 hundred into 10 tens, and so on.

Level 2 — Simple borrowing

Symbolic:

  742
- 358
-----

Ones: 2 − 8 not possible → borrow 1 ten. 12 − 8 = 4. Tens: (4 − 1) = 3, then 3 − 5 not possible → borrow 1 hundred. 13 − 5 = 8. Hundreds: (7 − 1) = 6, 6 − 3 = 3. Answer: 384

Level 3 — Borrowing across zeros

Visual:

  5004
- 2368
------

Ones: 4 − 8 not possible, but tens digit is 0, so borrow moves through the hundreds too. 5,004 = 4 thousands + 9 hundreds + 9 tens + 14 ones (after regrouping). 14 − 8 = 6; 9 − 6 = 3; 9 − 3 = 6; 4 − 2 = 2. Answer: 2,636

Level 4 — Checking with addition

Rule: If a − b = c, then c + b must equal a. Always check: 2,636 + 2,368 = 5,004 ✓

Worked example

Subtract 6,203 − 4,576

Step 1 — Ones: 3 − 6 not possible; tens digit is 0, so borrow travels to hundreds.
Step 2 — Rewrite 6,203 as 6 thousands, 1 hundred, 9 tens, 13 ones (after regrouping).
Step 3 — Ones: 13 − 6 = 7. Tens: 9 − 7 = 2. Hundreds: 1 − 5 not possible → borrow from thousands: 11 − 5 = 6. Thousands: 5 − 4 = 1.
Answer: 1,627
Check: 1,627 + 4,576 = 6,203 ✓

Common mistakes

Mistake	Why it happens	Fix
Subtracting the smaller digit from the larger one regardless of position	Ignoring borrowing rule	Always borrow when the top digit is smaller
Getting stuck when the next digit is 0	Not realising the borrow must travel further left	Keep borrowing through zeros until you find a non-zero digit
Forgetting to reduce the borrowed-from digit by 1	Rushing the subtraction	After borrowing, reduce that column's digit by 1 before subtracting
Not checking the answer	Skipping verification	Add the answer to the number subtracted — it should equal the original number

Quick check

623 − 275 = ? (348)
4,002 − 1,865 = ? (2,137)
8,000 − 3,456 = ? (4,544)
Check whether 2,636 + 2,368 = 5,004. (Yes)
Stretch: Find the missing number: 7,215 − ___ = 3,489. (3,726)

Revision tip: Practise one borrow-across-zeros problem daily (like 6,000 − 2,345) until it feels automatic.

Open the Practice tab for graded questions on Subtraction with Regrouping.

Subtraction with Regrouping