What is value of 20log10?

Answer 1

20 log 10 = log (10^20)

The actual value will depend upon the base use for the logarithm - "log" means logarithms taken to any base, and when calculated it gives to what power the base needs to be raised to get the original number.

Two bases are used a lot and have specific abbreviations:

* logs to base 10 are known as common logs and are usually abbreviated to "lg";

* logs to base e (= 2,71828...) are known as natural logs and are abbreviated to "ln".

On a scientific calculator, the [log] button is common logs ([lg]).

If [2][0][log][1][0][=] is entered on a modern Casio scientific calculator the result will be 20 × lg 10 = 20 x 1 = 20.

On an older (or different model without "natural entry") scientific calculator [2][0][×][1][0][log][=] will need to be entered

If natural logs are used: 20 log 10 = 20 ln 10 ≈ 20 × 2.303 +≈ 46.052.