What are useful strategies in sum and differences with decimals?

Answer 1

When you are lining up decimals to add or subtract, always line the decimals up before doing the problem. An example is:

1.468 + 0.0004 would be lined up this way:

1.468

0.0004

1.4684

If this is a bit confusing, you could add a zero to 1.468 and it would be 1.4680.

When doing subtraction, you would do the same. An example is:

4 - 0.086

4 can be written 4.0 or 4.000, so line then up like this:

4.000

-0.086

3.914