When you are solving an addition calculation with a two-digit number, you need to think about tens and ones. A place value chart can help you to see the value of each digit in a number.

Build, read, write (in standard and expanded form), and represent three-digit numbers ... 215. Two hundreds, one ten, five ones. 215, good job. - Base 10 blocks help us understand place value.

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 ...