Find the log of 9817. It's base 10 and we're using look up tables, so I looked it up, had to interpolate since we only had 3 digits of accuracy and got 0.9919 * 10^2 afterward since the original number is greater than 10. I checked this out in a calculator (Octave) and it checks out. However their answer says 3.9919

Whats the deal?

Question

Find the log of 9817. It's base 10 and we're using look up tables, so I looked it up, had to interpolate since we only had 3 digits of accuracy and got 0.9919 * 10^2 afterward since the original number is greater than 10. I checked this out in a calculator (Octave) and it checks out. However their answer says 3.9919

Whats the deal?

anonymous · Answer

The log of base 10 means, what power do you have to raise 10 to to get the number?  10 to the 1st power is 10, and your answer of slightly less than 1 will give slightly less than 10, so clearly that's not the correct log of 9817

anonymous · Answer

10^4 on the other hand, is 10,000, so a number slightly less than 4 is the right answer

anonymous · Answer

so I believe your interpolation method was not correct nor was the way you're using octave correct.

anonymous · Answer

Hmm thank you for clearing that up. Octave is definitely giving me odd results eg. log10(100) = 0 :S I'll keep working on it

anonymous · Answer

Usually calculators use 'e' as the base of log.  Here's a tip: since you know log base a of b = log(b) / log(a), whenever I use a calculator I always divide by log of my desired base.  That way I get the right answer no matter what the calculator is using as its log base.  So if I want log base 10 of 304, I'd type "304, log divided by 10 log"