When you're doing column addition, imagine each place value as a neighbor on a quiet street. The first neighbor tallies up all his digits, and-uh-oh!-he ends up with a two-digit number. He keeps the second digit for himself and gives the first digit to his neighbor on the left. The second neighbor tallies up all his own digits, and-look at that-he ends up with a two-digit number, too. He keeps the second digit and gives the first digit to the next neighbor on the left.
For some problems, we have to carry, or regroup, a digit to the tens place and carry a digit to the hundreds place (hundreds column). Take a look at this problem:
692
+ 238
First, we add the digits in the ones place: 2 + 8 = 10. We're going to have to carry or regroup. We write the ones digit, 0, in the ones place (ones column) and carry the tens digit, 1, to the tens place (tens column).
1
692
+ 238
0
Then we add the tens place: 1 + 9 + 3 = 13. We'll have to carry or regroup again. We write a 3 in the tens place and carry the 1 to the hundreds place.
1 1
692
+ 238
30
Finally, we add the hundreds place: 1 + 6 + 2 = 9. Write a 9 in the hundreds place. We're finished!
1 1
692
+ 238
930
