#### Answer

$18+11=29$
$18
+11=
29$
Adding vertically is an easier way of calculating.

#### Work Step by Step

First, add the digits in the ones column (each number's ones place) to determine the digit in the ones place of the sum: $8+1=9$
Next, add the digits in the tens column (each number's tens place) to determine the digit in the tens place of the sum: $1+1=2$
If the sum has $2$ in the tens place and $9$ in the ones place, it must be $29$.