To round the number 42.78 to the place of the underlined digit (which is the tenths place, represented by the digit 7), you look at the digit to the right of it (the hundredths place).
The number is:
- 42.778
The digit in the hundredths place (the digit to the right of the underlined 7) is 8. Since 8 is 5 or greater, you round up.
So, you round the 7 up to 8. Therefore, when rounding 42.78 to the tenths place, the result is:
42.8.