Question

Critique the reasoning of others. Oriana said that the difference between 9.298 and 3.01 was 8.997.

Was she correct? If not, what error did she make?

Answer 1

Answer: Oriana was not correct, because she didn't line up the decimal points of the numbers
`9.298` and
`3.01`

Explanation:

By definition, the "Difference" is the result of a subtraction.

In order to subtract the decimal numbers
`9.298` and
`3.01.`, Oriana needed to apply these steps:

1. Write one number under the other. The decimal points must be lined up:

`9.298 \\3.01-\\..........`

2. Since the decimal numbers must have the same number of decimal places, she needed to add zeros to the right side:

`9.298 \\3.010-\\..........`

3. Subtract the numbers and put the decimal point in the result:

`9.298 \\3.010-\\..........\\6.288`

Oriana was not correct, because she didn't line up the decimal points. Her procedure was:

`9.298 \\ 0\ 3.01-\\..........\\8.997`