Adding tens to a number

To add tens to a number like 34, only the tens change. 34 + 20: the 3 tens become 5 tens, and the 4 ones stay. The answer is 54.

You can also jump along a number line in tens: 34, 44, 54. Two jumps of ten is the same as adding 20.

A hundred square shows this well: each ten you add moves you one row down, and you stay in the same column.