When You Need to Borrow
Sometimes the digit you are subtracting from is smaller than the digit you are subtracting. That is when you borrow from the next column.
Example: 72 − 38
- Ones: 2 − 8. We can't do this! Borrow 1 ten from the tens column.
- Now ones = 12 − 8 = 4. Tens column is now 6 (was 7, gave 1 away).
- Tens: 6 − 3 = 3.
- Answer: 34
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Check Your Work!
Always verify subtraction by adding your answer back: 34 + 38 = 72 ✓. If it equals the original number, your subtraction is correct!
Subtracting Across Zero
Numbers with zeros in the middle (like 305 − 148) require borrowing across two columns. Take it one column at a time — borrow from the hundreds when the tens is 0.
305 − 148: borrow from hundreds to make tens = 10, then borrow from tens for ones. Work carefully column by column.