Column Method
Maths: Year 3 & 4 National Curriculum, topic 1.2.2
Column Addition
We can use column addition to add numbers together that are difficult to do mentally. Column addition is a way of writing down your working.
Column addition
- When adding using column addition, we need to line the numbers up in the columns which represent their place value.
Method
- When you use column calculations, you need to always start by adding the smallest column.
- This is on the right of the column addition calculation.
- Write the answer directly below the column as shown.
Method cont.
- Then add the next column of numbers,
Answer
- Continue to add the next column on the left until you have no more columns left to add.
- The final answer is the number you are left with below.
Carrying
- Sometimes the two digits in a column add up to make 10 or more.
- 8 + 6 = 14
- So we need to carry a 1 into the column on the left.
- This 1 is included when we go to add this column.
- 4 + 2 + 1 = 7
Column Subtraction
We can also use the column method to take numbers away from other numbers.
Column Subtraction
- When adding using column subtraction, we line the numbers up in the columns which represent their place value.
Method
- When you use column calculations, you need to always start by subtracting the smallest place value column.
- This is on the right of the column subtraction calculation.
- Write the answer directly below the column as shown.
Method cont.
- Then subtract the next column of numbers.
Answer
- Continue to subtract the next column on the left until you have no more columns left to subtract.
- The final answer is the number you are left with below.
Carrying
- Sometimes the top digit in a column is less than the bottom digit.
- So we need to borrow a "ten" from the column on the left as shown.
- We then take away the bottom digit away from the new top digit.
- We have to take away one from the digit we borrowed from.
Test yourself on Column Method
Which place value column do you start with when doing column addition?