Watch carries appear and travel, column by column
Column addition is the standard written method for adding two or more numbers together. You line the numbers up vertically so that digits with the same place value are in the same column — ones under ones, tens under tens, hundreds under hundreds — and then work through the columns from right to left, adding each one in turn.
When the digits in a column add up to 10 or more, you can't write the full total in that column. You write the ones digit of the total in the current column and carry the tens digit over to the top of the next column to the left, where it gets added in with the other digits there. This is called carrying (or regrouping).
You always add from right to left because carries only flow in one direction — from a lower place value column into the next higher one. If you started from the left, you wouldn't yet know whether a carry was coming from the right, and you'd risk writing wrong digits before you'd seen all the information.
Write numbers neatly with one digit per column, and always start by aligning the rightmost digit of each number. If the numbers have different numbers of digits, leave the missing positions empty — don't shift them. After adding, check your answer by estimating: round each number and add mentally to see if the total is in the right ballpark.
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