Three significant figures would be 87.1 m
In scientific notation it would be 8.71 x 10^1 m
Significant figures tells you how many total digits to hold in the number, so in this case it is three, so we keep three total digits, but we round up the tenths position because in the hundredths is 7. In order to write in scientific notation, the mantissa (or significand) must be between 1 and 10. The magnitude is then denoted by a power, the power is calculated by how many times the decimal is "moved" if it is to the left to get the mantissa, then it is a positive number, if it is moved to the right, then it is a number smaller than 1.
