how to find and use log tables

Urvashi Yadav , Meritnation Expert added an answer, on 10/12/12

Dear user!

To find the logarithm:

- We always express the number in the standard form using characteristic and mantissa.
- The standard form of a number a using characteristic and mantissa is a = m x 10
^{c}, where c and m are the characteristic and mantissa. - If a = m x 10
^{c }then log a = c + log m. To find the value of log m, we use the log table. Also,

Let us understand log calculation, with the help of an example.

Suppose we have to find log of 3.352 x 10 ^{ 11 } .

Taking log,

log(3.352 x 10 ^{ 11 } ) = log (3.352) + log(10 ^{ 11 } )

log(3.352 x 10 ^{ 11 } ) = log(3.352) + 11 log(10)

log(3.352 x 10 ^{ 11 } ) = log(3.352) + 11

To find log(3.352), we will look for the value in 33 ^{ th } row, 5 ^{ th } column, which is 5250. To this we add the mean difference of the 2 ^{ nd } column, in the same row, in the log table.

5250 + 3 = 5253.

Now, log(3.352) = 0.5253

So, log(3.352 x 10 ^{ 11 } ) = 11+0.5253 = 11.5253

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