Chapter 1 - Whole Numbers - 1.2 Adding Whole Numbers - 1.2 Exercises - Page 18: 8

$135+253+410=798$

First, add the digits in the ones column (each number's ones place) to determine the digit in the ones place of the sum: $5+3+0=8$ Next, add the digits in the tens column (each number's tens place) to determine the digit in the tens place of the sum: $3+5+1=9$ Then add the digits in the hundreds column (each number's hundreds place) to determine the digit in the hundreds place of the sum: $1+2+4=7$ If the sum has $7$ in the hundreds place, $9$ in the tens place and $8$ in the ones place, it must be $798$.