In this free video, students learn to add two or more digit numbers.

First - line up the numbers vertically so that the units digits are in the same column.

Second - add the units digits, the tens digits, and the hundreds digits. Adding the units digits, 9 + 5 = 14, which is the same as 1 ten and 4 ones, so put a 4 in the units column and carry a 1 to the tens column.

Third - add the tens digits, 1 + 3 + 2 = 6, and adding the hundreds digits, 1 + 0 = 1. So 139 + 25 = 164.

The final answer is called the "sum".