Worked examples
Two examples
Example 1
742 − 368 =
- Ones: 2 is less than 8, so borrow 1 from the tens: 12 − 8 = 4. The tens digit 4 becomes 3.
- Tens: 3 is less than 6, so borrow 1 from the hundreds: 13 − 6 = 7. The 7 becomes 6.
- Hundreds: 6 − 3 = 3. Check: 374 + 368 = 742.
Answer: 374
Example 2
4,003 − 1,267 =
- Ones: 3 is less than 7, and the tens and hundreds hold 0, so borrow from the thousands. The 4 becomes 3, and the zeros become 9s.
- Now: ones 13 − 7 = 6; tens 9 − 6 = 3; hundreds 9 − 2 = 7; thousands 3 − 1 = 2.
- Check: 2,736 + 1,267 = 4,003.
Answer: 2,736
Where this is taught: Quiz 3: Addition and Subtraction with Regrouping, “When the neighbor’s pocket is empty”
The drill
Ten problems
How many:
Type each answer, then press Check my answers at the bottom. Commas in large numbers are fine.Write each answer on the line. The answer key, with the reasoning, is on the last page.