Final answer:
When rounding numbers to the place of the underlined digit, we use a set of rules based on the dropped and retained digits. For example, when rounding 81.27, we round up to 81.3 because the dropped digit is 7 which is higher than 5.
Step-by-step explanation:
When rounding each number to the place of the underlined digit, we follow a set of rules. If the dropped digit is 5 or higher, we round up. If the dropped digit is lower than 5, we round down. If the dropped digit is 5 and there are non-zero digits following it, we round up. And if the dropped digit is 5 and the retained digit is even, we round down. For example, 81.27 rounds up to 81.3 because the dropped digit is 7 which is higher than 5. And 0.028675 rounds up to 0.0287 because the dropped digit is 7 which is higher than 5.