MathBench > Measurement

Logs and pH

Anti-logs

By the way, if you know the log value and you want to find the original value of the number, how do you do it?

Use the anti-log, of course!! The antilogarithm (antilog) is the number corresponding to a given log so...

the log of 1000 is 3 ... therefore ...

1000 is the antilog of 3

However, if your calculator doesn't have an anti-log key, you can raise 10 to the log, or use the 10x key. For example, the log of the pollen diameter was −4.5, therefore the diameter in metres is

10−4.5 = 0.0000316 m

... which is the same as 3.16 x 10-5 m or 31.6 µm

If you are using Google as a calculator, type "10^−4.5 = " and hit "Enter".

How big is a fly's eye? The log of the diameter is −3.1...

(To make this problem interactive, turn on javascript!)

I think I have the answer: 10−3.1 = 0.00080 m.