Wed February 25, 2009 By: Anubhav Sinha

General Question

Expert Reply
Wed February 25, 2009

First and foremost is to remember the rules of logarithms.

When you are taking product of two numbers, use

 log(mn) = log m +log n

if you are seeing the log of say 268.3, then you need to write 268.3as 2.683*100

100 is the second power of 10.

So you see the log of 2683 in the table and write it after 2.

So log(268.3)=2.4286

So you have seent  that the power of 10 is of importance here.

when you have to see the antilog after using the formula,

 remember that the decimal part of the number for which you are seeing the antilog must be positive.If it's not, then you need to make it positive.

e.g.  for seeing antilog(-1.723)




=-1+ (-1+1-0.723)

= -2+0.277

now see the antilogtable entry for .27 under the column 7

 that wil come out to be 1892

Since the integral part is -2, (a negative number )

 we follow the rule that there will be one zero (2-1=1) after the decimal point and then the antilog entry.

So antilog(-1.723)=0.01892

Next, if the  integral part of the number for which we have to see the antilog, is positve, then the number of places after the decimaal point will be integral part +1



here the decimal part is 2 which is non -negative.


in the antilog entry 2094, we will leave 3 places(2+1=3) from the left and put the decimal point.



If you have any more doubts on this, do send.

Also any particular calculations need to be checked, you can send it , we will solve it for you.


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