# [SOLVED] Easy Sig fig question

• Jan 30th 2010, 12:54 PM
Nismo
[SOLVED] Easy Sig fig question
79958.42

rounded to 3 shouldnt it be like 8.00 or 80.0?
• Jan 30th 2010, 01:04 PM
e^(i*pi)
Quote:

Originally Posted by Nismo
79958.42

rounded to 3 shouldnt it be like 8.00 or 80.0?

No, after all think about how far 8 and 80 are from 79958.42

What you should do is convert to standard form: $\displaystyle 7.995842 \times 10^4$

You can then round off the first part to 3sf which is 8.00 but you must bring back the 10^4 to give $\displaystyle 8 \times 10^4 = 80000$
• Jan 30th 2010, 01:39 PM
Quacky
79958.42
Remember that with significant figures, 0 counts in the context of a 10 or 100 and so forth, so for example, in 405, the 0 is significant, whereas in 0423, the 0 is not significant.
Therefore, when rounding this to three significant figures, the answer is 80000, as e^(i*pi) said.
• Jan 30th 2010, 04:59 PM
skeeter
$\displaystyle 80000$ has only one significant figure.

$\displaystyle 8.00 \times 10^4$ has three significant figures.
• Jan 31st 2010, 05:36 PM
Nismo
thxs everyone for the help.