Re: TI-92, HELP! Significative numbers!!!
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Re: TI-92, HELP! Significative numbers!!!
>> If you want a calculation to two sig. figs. set mode to FIX 2.
>
>on the 86 the cmd to do this is float. since the 86 also uses the fix cmd to
>set the decimal, I would assume that float is the correct cmd for the 92 as
>well.
You don't even know what significant figures are. In science, when measuring
you must always estimate the last digit. For instance, if the scale says
12.34 grams, the true value could be anywhere between 12.335 and 12.344 grams.
This introduces a fudge factor that must be eliminated by rounding when you
do calculations on the measurement. The rule is, when + or -, round to the
same number of decimals as the measurement with the fewest. When * or /,
round to the same number of significant figures as the measurement with the
fewest.
The float mode on the calculators only means that the number of decimal places
displayed adapts to the number. Float changes .50000 to .5, but keeps
.57498 as .57498. This has nothing to do with significant figures.
For instance, 12.5 * 3.65 = 45.625 in float, but the answer with the correct
number of sig figs is 45.6. Want to know more about sig figs? Read Chapter
one of any chemistry textbook. Otherwise, if you're going to guess in your
reply, say up front that it's only a guess.