Ok, I know this is a touchy subject in the world of the sciences, but allow me as a student, and now a, well still a student, but someone who in the next two days will hopefully be a highschool graduate to make a few things clearer. In the world of school science sigs figs are useless. If you are given a worksheet, sig figs make no sense, unless the sheet gives you a bit of a preface of “jonny was trying to conduct an experiment and took down these figures as his data.” Sig figs are not inherently a bad idea. However, when you are given an apple that has a velocity of 15 m/s and a mass of say 0.1kg, it makes no sense at all to say that its momentum is 2kg*m/s. This would make my head explode, maybe because I’m a bit of a mathmatician or something, but on a worksheet it seems as though we are given hypothetical exact values, not ones that arise from an experiment. I have come to understand their importance when it comes to a more real world process. It would be unwise to say that your left toe was exactly one inch across exactly with infinite presicion, because the fact is that the idea of anything being exactly an inch is a bit of a wierd consept. Say you have exactly one inch of atoms in a line. Where do you start measuring from? There is an electron cloud around the atom, and you could have a line of atoms that is over or under the inch, actually both, until you measure it. Yada yada yada wierd ideas and such, but it’s starting to make a bit more sense, I wish that schools maybe had a bit more for explanation of why you actually might want to use sig figs, rather than just not because it seems like a useless process that complicates everything for no reason and gives you the (right) wrong answer.