## how many place numbers to round to

Maria Zamarripa 1L
Posts: 30
Joined: Fri Apr 06, 2018 11:05 am
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### how many place numbers to round to

When doing a calculation and the number is really long on the calculator, how many places do we round to? and does it affect sig figs?

Andre-1H
Posts: 39
Joined: Fri Apr 06, 2018 11:01 am

### Re: how many place numbers to round to

I'm guessing you're talking about on a test/midterm where time is an issue. An easy way to do it is to look at the question and first, determine how many sig figs your answer will have. Let's say for instance your answer has 2 sig figs. When doing a calculation, there really is no need to multiply 1.3928328958 * 2.818239129392. You could just instead multiply 1.393*2.818 If you know how many sig figs you need, there really is no reason to do calculations with 5+ extra sig figs because they will just get rounded off anyways at the end.

Hope this helped, let me know if you need me to clarify

Maria Zamarripa 1L
Posts: 30
Joined: Fri Apr 06, 2018 11:05 am
Been upvoted: 1 time

### Re: how many place numbers to round to

Thank you for the clarification, just one more additional question, how do you figure out how many sig figs you will be needing at the beginning of the problem?

Posts: 30
Joined: Fri Apr 06, 2018 11:03 am
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### Re: how many place numbers to round to

Generally you would look at the information provided in the question. For the values given that you will use, whichever one has the lowest number of sig figs is the number of sig figs your answer should have.