1. The problem is to round the decimal 0.78 to the nearest tenth. 2. The rule for rounding to the nearest tenth is to look at the hundredths place (the second digit after the decimal point). 3. The decimal 0.78 has 7 in the tenths place and 8 in the hundredths place. 4. Since the hundredths digit (8) is 5 or greater, we round the tenths digit (7) up by 1. 5. Increasing 7 by 1 gives 8, so the rounded number is 0.8. 6. Therefore, 0.78 rounded to the nearest tenth is $0.8$.