Calculation of logarithms can be necessary for finding of values on the formulas containing indicators of degrees in quality of unknown variables. Two types of logarithms, unlike all others, have own names and designations are logarithms on the bases 10 and number e (irrational constant). Let's consider several easy ways of calculation of a logarithm on the basis 10 - a "decimal" logarithm.

## Instruction

1. Use the calculator which is built in the Windows operating system for calculations. For its start press the win key, select the Execute item in the main menu of a system, enter the Latin letters calc and press OK. In the standard interface of this program there is no function of calculation of algorithms therefore open in its menu the section "Look" (or press a combination of the alt keys + "and") and choose a line "scientific" or "engineering".

2. Enter number which has to stand under the sign of a decimal logarithm, and click on the button marked in the interface with the inscription log. The calculator will calculate and will show result.

3. Use any online service if your computer is connected to the Internet. In network there is a huge number of the websites with calculators various. Pass, for example, to the http://kalkulyatoronline.ru/index.html page and press the end key to miss the description of the calculator and to pass directly to calculation. Enter number which decimal logarithm should be calculated, and click on the button from same, as in the program calculator the inscription log. You will see result at once - this service does not send data to the server, and calculates everything directly in your browser.

4. If for any reason you do not wish to calculate a decimal logarithm as a logarithm on the basis 10, then it is possible to present it as private from division of a logarithm on e basis (Euler's number) of this number, on a logarithm on e basis from 10. Logarithms with the basis of e are called "natural": lg (x) =ln(x)/ln(10). To count a logarithm this non-standard way pass, for example, to the website of Google search engine and enter into a line of a search query ln(81)/ln(10) if it is necessary to find out value of a decimal logarithm for number 81. Google, by the way, can count it and a usual way that is if you enter request of LG 81. In both cases the result will be identical: 1.90848502.