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I'm not quite sure when to round off my significant figures when doing a problem that has multiple mathematical steps. For example, question E1 asks firstly for the number of atoms in 1.00mol Ag and then to multiply that number by 144pm to get a final length. I understand that I would have to multiply 1.00mol by Avogadro's constant getting 6.0221e10^23 atoms, would I round to 3 sig figs there and then multiply by 144pm, or wait until the final step to round?
I think you should maintain your rounding to the lowest number of sig figs that is given in the problem. For example, if the problem says there are 5.43 grams of Carbon and that is the lowest number of sig figs given in the problem, then your calculations should have 3 sig figs too.
To add on to what has already been said, it really helps if you store the value in your calculator as you are solving. That way, you get the most accurate answer. If you round as you go, your answer will probably be off by a few digits.
Never round off by sig figs in the middle of the problem, but keep in mind the sig figs of each new value you are continually using in a problem. At the end of the problem look at the supposed sig figs the values you used had and then round off to that number of sig figs.
If you round in between your answer could either be erroneously high or low (depending on whether or not you round up or down) and be off, so it's best to wait until the very end and keep all your number in your calculator if you can.
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