First set out the calculation with the two numbers organised in columns according to the place value of each digit. 17 has 1 group of ten and 7 ones. 24 has 2 tens and 4 ones. Image caption, ...

To add two-digit numbers, you need to think about place value. You start by adding up how many ones you have. If you have more than 10 ones, you can put a group of ten into the tens column.