## Amount of significant figures in calculations.

Or Fisher 1I
Posts: 35
Joined: Fri Feb 02, 2018 3:00 am

### Amount of significant figures in calculations.

Are we supposed to round calculations that aren't the final answers? How many significant figures am I supposed to use throughout the question and then how many do I need to use to calculate the final answer? Thanks.

Chem_Mod
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### Re: Amount of significant figures in calculations.

If you want the exact practice, you should only round at the end of the answer.
The rules for doing significant figures vary depending on if you are doing addition/subtraction, multiplication/division, or other mathematical operations. The rules vary depending on the mathematical operation, so I cannot say what is the exact number of digits to carry out since it will vary problem to problem. However, something to keep in mind is that you probably do not need all the trailing digits because most likely these will have little influence on the answer if you starting sig fig number is like 3-4. For clarification of this statement, please first read: https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=9&t=3195&sid=a6e8be8c358f6c2423fa82f3ff9d37a5

fara valdez
Posts: 48
Joined: Fri Apr 06, 2018 11:05 am

### Re: Amount of significant figures in calculations.

Typically, the easiest way to recognize how many significant figures to use is first to know that any non-zero digits and any zero digits in between are significant digits. Leading zero-digits are not significant. Usually in the question, they may already use the amount of sig. figs. in the number, and that amount is consistent in all the numbers used in their question. Also, there may even be a decimal point followed by the number in order to represent or show how many sig. figs. there are. Decimal points are useful because there is a way to know how many sig. figs. to use for the trailing numbers coming after by looking at its placement. If there isn't, then it's a bit harder to know for sure.