Question: are all acetone the same?
Answer: Practically, the number is rounded (up or down) both in science and in life. The term '100%' is for purities of 99.50% to 99.99%. Not all '100%' acetone is made the same. In fact, they differ in their purities (99.50% to 99.99%) and the contents of the impurities (the ones that make up the other 0.01% to 0.50%).