Line up the columns
Place ones under ones, tens under tens and hundreds under hundreds.
Good layout makes the written method much easier.
Year 3
Add and subtract numbers with up to three digits using formal written methods of columnar addition and subtraction
Line up hundreds, tens and ones carefully in columns to add and subtract accurately.
Lesson overview
Number - addition and subtraction
Column methods work when digits with the same place value are lined up underneath each other. We work from the ones column, then tens, then hundreds.
Column addition
347 + 212 = 559.
Add the ones, then tens, then hundreds.
Column subtraction
584 - 142 = 442.
Subtract the ones, then tens, then hundreds.
Worked example
Calculate 426 + 153 using columns.
- Line up the hundreds, tens and ones columns.
- Add the ones: 6 + 3 = 9.
- Add the tens: 2 tens + 5 tens = 7 tens.
- Add the hundreds: 4 hundreds + 1 hundred = 5 hundreds. The total is 579.
Try it
Check the column layout before you choose the answer.
Question 1
What is 231 + 145?
Question 2
What is 563 - 221?
Question 3
305 + 242 =
Question 4
Which answer is correct for 700 - 120?
Question 5
Why do we line numbers up in columns?
Common mistakes
Watch for these when working through the lesson.
- Not lining up the digits by place value.
- Starting with the hundreds instead of the ones.
- Writing the final answer in the wrong order.
Related topics
These ideas fit closely with this lesson.
- Add and subtract numbers mentally, including a three-digit number and ones, tens and hundreds.
- Estimate the answer to a calculation and use inverse operations to check answers.