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Calculation of antilog of a number using antilog table (mantissa table)

An antilog is the result of raising the base being used to the logarithm given or calculated. Put another way, it "undoes" what calculating the logarithm of a number does and simply returns that number.


Example 1:

Consider a number, 3.6325

Step 1:

Separate the characteristic part and the mantissa part.

From the given example,

the characteristic part is 3

the mantissa part is 6325

Step 2:

Find the corresponding value of the mantissa part by using the antilog or mantissa table.

First, find the row number that starts with .63 (3.6325), then the column for 2 (3.6325)

Now, the corresponding value is 42855

Download antilog table from here.

Antilog Table
.pdf
Download PDF • 1.01MB

Step 3:

Find the value from mean difference columns.

Again use the same row number .63 (3.6325) and find the value for column 5 (3.6325).

Now, the value corresponding to this is 50

Step 4:

Add the values obtained in step 2 and 3,

Now, the value is 42855 + 50 = 42905

Step 5:

Now insert the decimal point.

For this, first add 1 to the characteristic value. Now the place of decimal point is 4 (3 + 1). Then add the decimal point after 4 digits of the value obtained in step 4.

The value is 4290.5


So, the antilog value of 4.6325 is 4290.5

Example 2:

Consider a number, 2 .4412

Step 1:

Separate the characteristic part and the mantissa part.

From the given example,

the characteristic part is 2

the mantissa part is 4412

Download antilog table from here.

Antilog Table
.pdf
Download PDF • 1.01MB

Step 2:

Find the corresponding value of the mantissa part by using the antilog or mantissa table.

First, find the row number that starts with .44 (2 .4412), then the column for 1 (2 .4412)

Now, the corresponding value is 27606

Step 3:

Find the value from mean difference columns.

Again use the same row number .44 (2 .4412) and find the value for column 2 (2 .4412).

Now, the value corresponding to this is 13

Step 4:

Add the values obtained in step 2 and 3,

Now, the value is 27606 + 13 = 27619

Step 5:

Now insert the decimal point.

For this, first add 1 to the characteristic value. Now the place of decimal point is 3 (2 + 1). Then add the decimal point after 3 digits of the value obtained in step 4.

The value is 276.19


So, the antilog value of 2.4412 is 276.19



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