Why 100 ml is 1 sig fig from below answer?

Glucose = C6H12O6



Molecular mass = 6(12) + 12(1) + 6(16) = 180 grams / mole



(86 mg / 100 ml)(1 gram / 1000 mg)(1000ml /liter) = 0.86 grams / liter



M = grams / (mol. mass)(liters) = 0.86 grams / 180 grams / liter = 4.77 Exp -3 M or 0.00477 M



Answer: 0.005 M (one significant figure because of "100 ml")

Why 100 ml is 1 sig fig from below answer?
100 ml is one sig fig because doesn't have the decimal at the end like this 100. (if this is the case, there are 3 sig fig)