The sum of more that two numbers can be found by adding
each column from right to left, starting with the ones place.
First, add the ones column (8 + 8 + 2 = 18). Write the 8 in the ones place of the
sum, and carry the 1 to the
tens column.
Then, add the tens column (
1 + 9 + 8 = 18). Write the 18 in the
sum.