Sig Fig Rules

[Caroline Zepecki]

It has been a few years since I've been in chemistry, and I was hoping to clarify some of the basic sig fig rules. Is it customary to round to the hundredths or the thousands place when presenting a mass value (g) as your answer?

Also, do the rules for this vary greatly based off of what type of problem you're solving?

[Kate Osborne 1H]

Typically the amount of sig figs you have in your final answer is equal to the amount of sig figs in the given number that has the least sig figs. So if you were given two initial masses, one with 3 sig figs and one with 4, and your final answer was also a mass you would most likely round to 3 sig figs.

[Sofia Barker 2C]

Rounding depends entirely on the sig figs of the values presented in the question of the problem. You always want your final answer to reflect the same number of sig figs as the least precise value (the number with the least amount of sig figs) given in the question.

For example, when multiplying 15 by 3.55, the actual result would be 53.25. However, because the number 15 has two sig figs, you would round to 53 to match the same amount of sig figs.

When you are working through a complex problem with multiple steps, you can keep extra sig figs in your values during intermediate steps because it ensures that your final answer is as accurate as possible. Once you have your final answer you can apply the rules of sig figs.

[SajaZidan_1K]

It has also been some time since I have reviewed sig figs and I recommend that you look up worksheets online to practice the common sig fig rules. Your sig figs in your final answer should match the smallest sig fig value in the problem, but be sure to remember the sig fig rules. For instance, review when zero is considered a sig fig and the importance of a decimal point in determining some sig figs. To practice, just look up sig fig worksheet and a bunch of resources pop up for you to practice determining what numbers are considered sig figs. This will help you memorize the various rules of sig figs.