Sig figs (fuck this shit)

[Cream Soda]

Doing some online homework and I had a quick question about sig figs.

Do you truncate at every step, or just at the end? There aren't multiple choice and if you don't enter it exactly 100% correct, its wrong.

[SephYuyX]

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[Cream Soda]

slow clap.gif

[Olo401]

Seph yer my hero.

[foopy]

@seph:




@cream:

[solanis]

lol sig figs, christ

pretty sure you round at the end, otherwise you're compounding error at each step

[Cream Soda]

Yea, this teacher is a dick. He docks up to half a letter grade for a sig fig error (last test I got a 79 instead of an 84 because my sig figs were off in one problem, -5 in a 15 point problem, rest was correct)

[Pirian]

Uhhh don't round during any part of the problem until the end? Unless you're forced to do it by hand, but I've never had a class that gave an ungodly long number.

ITT: it's called a calculator. It calculates, and shit

[Enkidu]

Well you use sigfigs because the argument is that if you have a number measured to a certain degree of accuracy, you can't get a more accurate number from a calculation, right? In that case, you should have to round to sigfigs for every calculation.

Not sure though, I hate sigfigs and never use them.

[Furtwangler]

Only round at the end.

[Jaybar]

I've always rounded at the end but that's because my calculator can handle a complex equation at once instead of in steps (depending on equation of course).

[Knightmare]

Sig figs is done on every calculation.

Addition/Subtraction:
Your calculated value will have the same number of digits to the right of the decimal point as that of the least precise quantity.

Multiplication/Division:
The number of sig figs in the final calculated value will be the same as that of the quantity with the fewest number of sig figs used in the calculation.

[Woozie]

As others have said, only at the end.

[Xcrunner]

I would say only at the end because rounding in the middle of calculations introduces error

[plue]

IIRC you keep the long number until the end, then follow the rules for sig fig rules to get the right amount of decimal places in the end. Otherwise, do your shit on Excel and cock punch your prof for being a dumbtard...

[Psion]

As others say, you only round at the end, but you remember the number of sig figs from all variables used and the lowest number of sig figs gets applied to the final answer.

And any conversions, like 1 M = 1000 mm, are assumed to have infinite significant figures.

[Diamicles]

Well you use sigfigs because the argument is that if you have a number measured to a certain degree of accuracy, you can't get a more accurate number from a calculation, right? In that case, you should have to round to sigfigs for every calculation.

this is the most applicable way to use sig figs, but YMMV.

really it's a limiting factor of your most accurate measured number. if you aren't using a limiting factor, then round at the final step of the calculation.

[Talus]

Keep as many digits as you can while you're solving the problem, and then the correct number of sig figs usually varies according to the teacher's preference. You will compound rounding errors if you truncate at every step of the problem, assuming it's multi-step. BUT... rounding can be useful if you have to do a multi-step calculation in your head, just remember if you round up on the first step, round down on the second step to get a rough answer. Most of the time though, you keep as many significant figures as the shortest number given in the problem.

For some problems, there is a logical number of sig figs to keep because of a convention, like calculating a player's batting average is always three significant digits. You always see a player is hitting .279, not .2791 or .27917. What I've seen a lot is they prefer if you use the # of significant figures equal to the shortest given quantity in the problem, so if the shortest given is 45.6, but there are also 54.14, and also 52.251, use 3 sig figs. Make sense?

[Alvein]

Best way I learned sig figs was to visualize it with a real world application.
Imagine you're measuring .5L of water. You measure it in a one liter beaker and all you have is one line in the middle for half a liter and it is labeled .5.
You're going to be limited to one significant figure at the end because your beaker was incredibly inaccurate and didn't give you a very good estimate of how much water you actually had to start with. Every time you measure something the accuracy of your data is limited by the tools you measure with.

I hope this helps, it made sense to me when I was learning it in chem lab.

[Nyima]

So using sig figs I can calculate that half of that .5L of water is .3L of water.

Sig figs how I love you.