EPTi dont really get it.
Say i need to divide 10.27 by 10.2, the answer should feature 3 significant numbers?
doesnt really make sense, since one of my measurments is only correct to the tenth, how can the answer have 2 digits after decimal?-.-a
Significant numbers question.
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Sfydjklm
United States9218 Posts
i dont really get it. Say i need to divide 10.27 by 10.2, the answer should feature 3 significant numbers? doesnt really make sense, since one of my measurments is only correct to the tenth, how can the answer have 2 digits after decimal?-.-a | ||
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ColdSoup
United States447 Posts
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Sfydjklm
United States9218 Posts
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SChasu
United States1505 Posts
<--terrible explainer... | ||
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Sfydjklm
United States9218 Posts
On September 15 2005 17:47 SS-guy wrote: if you mean it has like .004 or w/e there are still 3 significant digits. its not significant by a place. its significant by how many numbers there are. my question is why there should be 2 places after the decimal in the answer, when my worst measurement's accuracy is only 1 digit. | ||
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AK-Nemesis
2005 Posts
10.27 has 4 sig fig 10.2 has 3... you use the least, which is 3 sig fig.. so your answer is only up to the tenth... what is so hard about this? if you don't get it.. i suggest you drop this course, whatever comes after this is a lot more harder than sig fig | ||
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Sfydjklm
United States9218 Posts
On September 15 2005 17:56 AK-Nemesis wrote: 10.27 * 10.2 10.27 has 4 sig fig 10.2 has 3... you use the least, which is 3 sig fig.. so your answer is only up to the tenth... what is so hard about this? if you don't get it.. i suggest you drop this course, whatever comes after this is a lot more harder than sig fig how is it up to 10th if there is 3 sig figures? its gonna be 1.01 I am not asking what the answer is I am asking why its not treated like addition, for example, where the places after decimal are counted. p.s.: Its division not multiplication joo | ||
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AK-Nemesis
2005 Posts
On September 15 2005 17:58 Sfydjklm wrote: how is it up to 10th if there is 3 sig figures? its gonna be 1.01 I am not asking what the answer is I am asking why its not treated like addition, for example, where the places after decimal are counted. p.s.: Its division not multiplication joo my mistake about saying the tenth thing, once again i posted watching reading the entire post, sorry but still, the sig fig is just done that way, and it has a good reason for it altho i don't remember it exactly and don't want to bother finding out | ||
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teh leet newb
United States1999 Posts
On September 15 2005 17:47 SS-guy wrote: if you mean it has like .004 or w/e there are still 3 significant digits. its not significant by a place. its significant by how many numbers there are. That is incorrect. Placeholder digits do not count towards sig figs. Final zeros, however, do. Ex: 0.00009000 has 4 sig figs (9000). To the OP: Yeah, as AK-Nemesis said, multiplication/division isn't treated like addition/subtraction because well, that's just the way it is. I'm only in 10th grade chem, so I haven't learned why yet -_-; | ||
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Chibi[OWNS]
United Kingdom10597 Posts
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Ender
United States294 Posts
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Sfydjklm
United States9218 Posts
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Chill
Calgary25979 Posts
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Chibi[OWNS]
United Kingdom10597 Posts
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ArseniC-2
United States131 Posts
On September 15 2005 18:33 teh leet newb wrote: That is incorrect. Placeholder digits do not count towards sig figs. Final zeros, however, do. Ex: 0.00009000 has 4 sig figs (9000). Yep, SS-guy was wrong. On September 15 2005 18:46 Ender wrote: Look, just think about it this way: when you're doing a problem, you're answer can't be any more accurate the least bit of information you have. So if you have two pieces of information, like 1.23 or 2.4 in the beginning, you're answer can't be any more exact than the least accurate information you have, in this case 2.4 because it has the least amount of significant digits. Sig fig are just a way to quantify the accuracy of data. A lot of teachers dont even care about sig fig, since ideally you're supposed to round every number you get in every step of a problem. But since most chemistry and physics teachers just want their students to learn chemistry or physics, they dont care much. Still, it's not too hard to use it. He is right too. My H chem teacher was a nutcase, and we had to do everything with sig. figs, no matter how minor, and if he messed up sig figs even slightly, we lost at least 1/2 credit for the entire problem. | ||
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HeadBangaa
United States6512 Posts
On September 15 2005 17:56 AK-Nemesis wrote: Haha, you tried to be condescending but made an ass out of yourself :p10.27 * 10.2 10.27 has 4 sig fig 10.2 has 3... you use the least, which is 3 sig fig.. so your answer is only up to the tenth... what is so hard about this? if you don't get it.. i suggest you drop this course, whatever comes after this is a lot more harder than sig fig | ||
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1INK
United States630 Posts
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Bill307
Canada9103 Posts
10.2 ---------------- = 1.02 1.00 x 10^1 The answer is 1.02. Do you see why it is accurate to 2 decimal places even though the original (10.2) is accurate to 1 decimal? In general, the accuracy of a number does NOT depend on the # of decimal places! Maybe you just see it that way because almost every example you've encountered in real life so far has been like that. But in reality, the accuracy of a number depends on the # of significant digits, NOT JUST THE DECIMALS! Example: "6,500 people have been confirmed dead." How many significant digits does this have? Probably just two: 6 and 5. This means that there were between 6,450 and 6,549 deaths, because all of these numbers round to 6,500. In contrast, if all four digits were significant, then there were EXACTLY 6,500 deaths. Now let's make a trivial change to this figure. We can also say that 6.5 thousand deaths have been confirmed. Or, we can say that 0.0065 million deaths have been confirmed. 6,500 has 0 decimal digits 6.5 has 1 decimal digit 0.0065 has 4 decimal digits But they ALL have TWO significant digits. They are all accurate to 2 digits. This is an example of why the # of significant digits is NOT the # of decimal digits. | ||
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Syst[eM]
335 Posts
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Luhh
Sweden2974 Posts
On September 15 2005 17:44 Sfydjklm wrote: In a calculation involving multiplication, division, trigonometric functions, etc., the number of significant digits in an answer should equal the least number of significant digits in any one of the numbers being multiplied, divided etc. i dont really get it. Say i need to divide 10.27 by 10.2, the answer should feature 3 significant numbers? doesnt really make sense, since one of my measurments is only correct to the tenth, how can the answer have 2 digits after decimal?-.-a Highest range compared to lowest range by numbers given in the example? 10.274/10.15=1.012.. 1.01 10.265/10.24=1.002.. 1.00 1.01=/=1.00 Cute. Though this was an extreme example... | ||
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