Am I the only one that does this?

When I get an answer in my calculator, I write down all of the decimal places until I get to one that is below 5 because I'm too lazy/indecisive to actually pick a place to round and do it.

I'm talking 6 or 7 places sometimes.

I can't be the only one?

Yes, You are some kind of weirdo.:tongue2:
Anything more than two decimals is usually lying.

DaveC426913
Gold Member
Concurrence. Weirdo.

Not only do I do that, if the 5 comes too soon (within 5-8 digits), I will continue on to the next 5. No idea why I do this. Intermediate values, oh wow, I save 20 places sometimes...

DaveC426913
Gold Member
No idea why I do this.
It is merely a quirk, Quark.

arildno
Homework Helper
Gold Member
Dearly Missed
I always seek the double 3's.

Maroc
Gold Member
Anything more than 2 decimals is a no go in my books :P

Staff Emeritus
I take off points for insignificant digits.

There are no insignificant digits in my math. Usually it's pure until the answer pops out in terms of pi. Then I can take the decimal place as far as I like. This isn't physics.

Usually I look for a 0, 1, or 9. Those are my happy number rounding places.

As a rule of the thumb, I usually use as many significant digits as the question has.

jtbell
Mentor
If it's the final answer to a question, it should be rounded to whatever number of sig figs is appropriate for the initial input numbers.

If it's an intermediate answer, it should stay in your calculator (that's what your calculator's memory is for) and not be written down at all, unless your question asks you to show that answer also. In that case you should round off the written version appropriately, but use the unrounded version in the calculator for further calculations.

Gold Member
I round $e$ to 3. Is that bad?

Staff Emeritus
Not as bad as rounding it to 4.

I round $e$ to 3. Is that bad?

No joke, my physics professor usually uses 10 for g when working examples.

FlexGunship
Gold Member
I round $e$ to 3. Is that bad?

Not as bad as rounding it to 4.

Gentlemen!! We have a winnar!

russ_watters
Mentor
I take off points for insignificant digits.
As an engineer, I have too many assumed values in my calcs for sig figs to matter.

Pythagorean
Gold Member
I take off points for insignificant digits.

And this is basically how I stopped the habit in my undergrad

If it's the final answer to a question, it should be rounded to whatever number of sig figs is appropriate for the initial input numbers.

See, my problems are exact. It's not until the final calculation that things get decimal-ized.

I don't do it for final answers, because then its just wrong, its assuming a known value for values that aren't known (or equivalently, assuming that all decimal places after the given measurement are zeros)

You will find it surprising how many students at the college level don't know the reasoning behind significant figures and think that more decimal places means a more accurate answer.

1.3 meters is not 1.30 meters, it means we stopped measuring after a tenth of a meter.

I never learned that concept in school when I learned about significant figures. It only came to me when actually doing lab work.

1.3 meters is not 1.30 meters, it means we stopped measuring after a tenth of a meter.

I never learned that concept in school when I learned about significant figures. It only came to me when actually doing lab work.

I did learn that. My most confusing times currently are when I get to the end of a probability question and the final move turns out an enormous fraction which practically requires a decimal conversion to be useful comparatively. How far do I take it? As far as I like is my guess. So, that's to a 0, 1, or 9.

lisab
Staff Emeritus
Gold Member
I don't do it for final answers, because then its just wrong, its assuming a known value for values that aren't known (or equivalently, assuming that all decimal places after the given measurement are zeros)

You will find it surprising how many students at the college level don't know the reasoning behind significant figures and think that more decimal places means a more accurate answer.

1.3 meters is not 1.30 meters, it means we stopped measuring after a tenth of a meter.

I never learned that concept in school when I learned about significant figures. It only came to me when actually doing lab work.

A corollary to that observation: some people think a reading is more accurate if the instrument display is digital .

However, seeing hundreds of cases where the average of 30 integers between 0 -10 are cut to one digit, maybe we are loosing a wee bit of information. On the other hand, none of my kids has 2,184736 children. It's not doable. :tongue:

Gold Member
See, my problems are exact. It's not until the final calculation that things get decimal-ized.

Wait, wait. Let's get our terminology correct, here. Murdering a perfectly good symbol is decimation.