Column addition is a formal method of addition that involves setting out the calculation in place value columns. This simplifies the calculation because you only ever need to add the digits in one column at a time, starting with the ones column then moving onto the tens column, then hundreds, then thousands.
Let's look at an example:
To add 26 and 53, start by setting out the calculation so that the digits are split into place value columns.
Start with the ones column. In this case, you add 6 and 3 to make 9. Record the sum of the ones under the ones column.
Next, add the numbers in the tens column. 2 and 5 make 7. Record the sum of the tens under the tens column. This represents 70.
There are no digits in the hundreds column so the final answer to 26 + 53 = 79.
If the digits in a column add up to less than ten, you simply record the sum under the ones. If the digits add up to more than one, you need to exchange the ten. In other words, you move the ten into the tens column.
Let's look at an example:
To add 43 and 39, start by setting out the calculation so that the digits are split into place value columns.
Start with the ones column. In this case, you add 3 and 9 to make 12. Because this is dealing with ones, we only record the 2 in the ones column. We then exchange the ten ones from twelve into one ten. We record this 1 ten in the tens column underneath the answer row.
Next, add all the numbers in the tens column, including the 1 ten we exchanged from adding three and nine. In this case, 4 + 3 + 1 equal 8, which is recorded underneath the tens digits. This represents 80.
There are no digits in the hundreds column so the final answer to 43 + 39 = 82.
The process is the same for two-, three- and four-digit numbers (or numbers of any size). You simply move along the place value columns, starting with the ones, then moving left to the tens, then hundreds, then thousands, etc., until there is nothing left to add.
Here's another example:
To add 257 and 496, start by adding the ones. In this example, 7 and 6 equal 13. We have to exchange the ten ones into one ten.
Next, we add the digits in the tens column. 5 + 9 + 1 is 15. Again, we need to exchange ten tens into one hundred.
Next, add the digits in the hundreds column. 2 + 4 + 1 is 7. This represents 700.
There is nothing left to add so the final answer to 257 + 496 = 753.
