## Monday, 21 November 2011

### How to calculate logarithm reduction and log division in excel

How to calculate logarithm reduction and log division in excel. By using Microsoft Excel, we can perform the calculation of logarithms. In this post specifically discussed about how to use a logarithmic reduction formula and the division of the logarithm.

In general, how to write formulas / functions in excel logarithms is using syntax:

LOG (number, base)

with:
Number is the positive real number for which you want the logarithm.
Base is the base of the logarithm. If base is omitted, it is assumed to be 10
.

A simple example application of the reduction formula and the distribution of the logarithm can be seen below
ª log b / c = ª log b - log c ª

To calculate in Excel can follow the following procedure:

1. Create a table as below
Column A is the logarithmic base
Columns B and C is filled with data
Column D and E will filled with logaritm formula

2. Perform calculations by fitting logarithmic formula
a.  in cell D4 , type the formula
= LOG (B4/C4, A4)
b. in cell E4, type the formula
= LOG (B4, A4) - LOG (C4, A4)

That can be seen
In line 4, ª log b / log b c = ª - ª log c = 10 log 8 / 4 = 10 log 80-10 log 4 = 0.301
In line 5, ª log b / log b c = ª - ª log c = 2 log 9 / 7 = 2 log 9-2 log 7 = 0.3625