The number 25 has 2 tens and 5 ones. Now let's write this out as a column addition to work out the answer. You can use place value headings to help. Start with the column furthest to the right.

This means breaking a number up into tens and ones, or hundreds and tens, to help with the addition. If the two numbers in a place value column add up to ten or more, you must regroup. This means ...

Use “tens” and “ones” to explain the meaning of a two ... the place values and explain the thinking involved. Understand addition as “putting together” and “adding to.” ...