How do you show the group of digits that repeat in a repeating decimal?

1. By underlining them
2. By printing them in italics
3. By putting a bar over them
4. By putting them in parentheses

3. By putting a bar over them

The correct answer is 3. By putting a bar over them.

The correct answer is option 3: by putting a bar over them.

To show the group of digits that repeat in a repeating decimal, a bar is typically used to indicate the repeating pattern. This bar is placed over the digits that repeat. For example, if the decimal 0.3333... is written, the repeating digit "3" would have a bar over it to show that it repeats.

It is important to note that the bar is sometimes omitted for convenience, especially when the repeating pattern is a single digit. In such cases, parentheses can be used to indicate the repetition. So in some instances, option 4: by putting them in parentheses may also be seen, but the more commonly used method is by using a bar over the repeating digits.