# Significant digits in calculation

1. Jan 25, 2010

### php006

Hello everyone:
I am trying to figure out the how many significant figures (sf), should I keep in the final
answer for multiplication and division
1. How many hours and minutes are 20 kiloseconds?

2.

3. for hours: 20*10e3 / 3600 = 5.5555 hrs
20 has only 1 significant figure (trailing zero doesn't count), hence the answer should have 1 sf, that means I should round answer to the single digits. my final answer is 6 hr. My book give 5.6 hr as the answer.
please let me know my approach is correct

for minutes 20*10e3 / 60 = 333.333 minutes
keep only 1 sf in the result,that leads my answer to 333 minutes
my book give 330 and the final answer

2. Jan 26, 2010

### Ouabache

Your book appears to be choosing 2 significant digits. However you could just as well choose 3 sf and still be correct. I would state what I'm using for sf, in my solution. To 3 sf, hours would be 5.56hr. If you see the answer in your book as 5.6hr, you should realize, both answers are correct.

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