+9 | +0.7 | |||

1.6 | 10.6 | ? |

When adding numbers, it can be helpful to decompose the second number using the place value method and then use the arrow method to decrease the first number by each place value
For example, if we have 2.25 + 6.53

- Decompose 6.53 into 6 ones, 5 tenths, and 3 hundreths
- Grow 2.25 by +6 (=8.25)
- Grow 8.25 by +0.5 (=8.75)
- Grow 8.75 by +0.03 (=8.78)