Definition
Column addition
Column addition adds numbers by lining up equal place values in vertical columns.
What it means
Stack the numbers so ones are under ones, tens under tens, and so on. Add one column at a time, usually from the ones. If a column makes 10 or more, write the digit for that place and exchange each complete group of 10 for 1 in the next higher column.
Remember it
Same places stand in the same lane.
Example
Add 268 + 157. Ones: 8 + 7 = 15, so write 5 and exchange 1 ten. Tens: 6 + 5 + 1 = 12, so write 2 and exchange 1 hundred. Hundreds: 2 + 1 + 1 = 4. The sum is 425.
Watch for
Digits line up by place value, not just by the edge of the written number. With decimals, the decimal points line up.
Common mix-up
An exchanged 1 means one of the next place, not one extra unit: 10 ones become 1 ten, and 10 tens become 1 hundred.
Exact meaning
Column addition is a written addition method that aligns digits with the same place value, adds each column, and records any exchange into the next higher place.