Step-by-step Maths Level 4 · Column addition and subtraction · Summary
Step-by-step Maths Level 4 Column addition and subtraction: summary and key words
Part of the Step-by-step Maths Level 4 column addition and subtraction chapter. Chapter overview · whole chapter on one page
Chapter summary
| Skill | Method |
|---|---|
| Mental addition and subtraction | Change only the column that matches the number; check other digits |
| Column addition | Add from the ones; carry 1 when a column is 10 or more |
| Column subtraction | Subtract from the ones; exchange 1 from the left when the top digit is too small |
| Subtraction across zeros | Go left to the first non-zero column; each zero passed becomes 9 |
| Estimate and check | Round to the nearest 1000 to estimate; use the inverse to check |
Can you…?
- I can add and subtract a ten, a hundred or a thousand in my head
- I can add two four-digit numbers in columns, carrying across columns
- I can subtract two four-digit numbers in columns, exchanging where needed
- I can subtract across a zero in the middle of a number
- I can estimate, check with the inverse, and find a missing number
Key terms
- carry
- move a ten to the next column on the left when adding
- exchange
- break 1 ten into 10 ones (or 1 hundred into 10 tens) when subtracting
- estimate
- a sensible guess of the answer, found by rounding
- inverse
- the operation that undoes another: addition undoes subtraction