College Math Placement Practice Test

To find the sum of 22.9 and 0.5 after aligning the decimals, it’s important to first position both numbers vertically so that the decimal points line up. This alignment clarifies how to add the decimals correctly.

When we write it out, it looks like this:

```

22.9

+ 0.5

-------

```

Now, we can add starting from the rightmost digits.

1. In the tenths place, we have 9 from 22.9 and 5 from 0.5. When we add these together, we get 9 + 5 = 14. We write down 4 and carry over 1 to the whole number part.

2. Next, in the units place, we add 2 (from 22.9), 0 (the placeholder from 0.5), and the carryover 1. So, 2 + 0 + 1 = 3.

3. Finally, in the tens place, we add 2 from 22.9 with nothing from 0.5, which gives us 2.

Putting it all together, the overall sum is:

```

22.9