Addition in columns is a method used to add together numbers of more than one digit. It works for small numbers, but just as well for very large numbers. Once the techniques of adding and carrying are mastered any collection of any size of numbers can be added together. Column addition is typically first taught from Year 4 onwards after learning addition by partitioning in Years 3/4.

## How to do Column Addition

The numbers to be added together are written down one on top of the other so that the units, tens, and hundreds etc of each number are aligned. For example, adding 23 to 67 the 7 and 3 are aligned since they are the units, and the 2 and the 6 are aligned as they are the tens.

First the numbers in the units column (right hand column) are added together. If the total is less than 10, then the total is written in as the units part of the final answer. If the total is 10 or more, then we split the total into its units and tens components - e.g. 23 is made up of 3 units and 2 tens, 46 is made up of 6 units and 4 tens. The number of units from the total is then written in as the units part of the final answer, and the number of tens from the total is carried over to the tens column - typically being written underneath the answer in the tens column.

This simple process is then repeated for each of the remaining columns working from the units to the tens to the hundreds and so on moving from right to left until all the columns have been added and the final answer obtained.

Column addition is much better demonstrated than explained, so please try out our automatic column addition demonstrator. Start with level 1 and step through the levels to see exactly how column addition works as things get more complicated.

Level 1 - Add two 2-digit numbers (no carry).
Level 2 - Add two 2-digit numbers (carry 1's to 10's).
Level 3 - Add two 2-digit numbers (carry 10's to 100's).
Level 4 - Add two 2-digit numbers (carry 1's and 10's).
Level 5 - Add two 3-digit numbers (no carry).
Level 6 - Add three 3-digit numbers.
Level 7 - Add four 3-digit numbers.
Level 8 - Add four 4-digit numbers.
Level 9 - Add five 5-digit numbers.

press F5 to repeat a level with new numbers.

L1, L2, L3, L4, L5, L6, L7, L8, L9

Alternatively, you can enter up to five numbers yourself below to see how they should be added together using column addition.

The Question
513
+103

513
+103

3 + 3 = 6
so enter 6 in the 1's column of the answer.

513
+103
6

513
+103
6

1 + 0 = 1
so enter 1 in the 10's column of the answer.

513
+103
16

513
+103
16

5 + 1 = 6
so enter 6 in the 100's column of the answer.

513
+103
616 