How do you write 0.85 as a fraction?

To write 0.85 as a fraction, you need to understand that the decimal point separates the whole number part from the fractional part. In this case, 0.85 can be expressed as 85/100 because the decimal point is two places to the right of the 5 in the hundredths place. This fraction can be simplified by dividing both the numerator and denominator by 5 to get 17/20, which is the simplest form of the fraction representing 0.85.