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So I was working with this expression:

$1111 = 5 * 2^t$

after working it out until here

$2.346744/0.301029 = t$

I decided to use a calculator to know the value of $t$ just for fun. Using windows 10 calculator I got the value of $7.7957406097086991618747695404762$.

I was typing the exercises in Microsoft Word using the Design Equation functions and then under the Calculate option I hit the option that says: "Solve for t" and got this value instead: $t=782248100343$.

The lesson I was following on KhanAcademy ended up showing Sal using the ti-85 emulator which ended up with the result: $7.7957150065$.

So I am a little confused why so many different values?

I do understand that I only used 6 digits when performing the division which is not how Sal did it (he performed the division of logarithms directly) but In word and Microsoft Calculator I did have the same values so at least there the results should be exactly the same.

Any reasons why this might not be the case?

Reference: Link to lesson in question
Disclaimer: Im not really sure this question belongs here but is about math so probably some of you might know the answer.

RaptorX
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  • That second one is weird. The other two are explained by roundoff. – Ian May 23 '16 at 20:43
  • Well, I can tell you right away that the MS Word option is the inaccurate one. – Neil May 23 '16 at 20:44
  • On the Casio fx-115MS, I agree with the TI-85 emulator to the limit of my display: $ \ 7.795715007 \ $ . As a subscriber to Wolfram Alpha, I could push it for more digits than the standard output and got $$ 7.795715006501729645500702730726712282633251671625104724 , $$ and could have asked for more. Interestingly, it disagrees with the Windows calculator early on (I suspect there is a limitation in the Windows evaluator for logarithms). The MS Word result looks like you may have made an input error. – colormegone May 23 '16 at 21:06
  • I copy pasted all the time because I suspected a typing error. Still, I always expected less accuracy in terms of less digits (memory limits) but never different numbers. – RaptorX May 31 '16 at 05:48

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