How to Do Antilog
Separate the characteristic and the mantissa., Use the antilog table to find a corresponding value for your mantissa., Find the value from the mean difference columns., Add the values obtained in the previous steps., Insert the decimal point.
Step-by-Step Guide
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Step 1: Separate the characteristic and the mantissa.
Consider the number under observation.
The characteristic is the part that comes before the decimal point; the mantissa is the part that comes after the decimal point.
Antilog tables are arranged with respect to these parameters, so you need to separate them.
As an example, say you need to find the antilog for
2.6452.
The characteristic is 2, and the mantissa is
6452. -
Step 2: Use the antilog table to find a corresponding value for your mantissa.
Antilog tables are easily available; you may have one in the back of your mathematics textbook.
Open the table and look for the row number consisting of the first two digits of the mantissa.
Then find the column number equal to the third digit of the mantissa.
In the example above, you would open the antilog table and find the row number beginning with .64, then the column for
5.
In this case, you would find that the corresponding value is
4416. , The antilog table also includes a set of columns known as “mean difference columns.” Look at the same row as before (the row corresponding to the first two digits of your mantissa), but this time, find the column number equal to the fourth digit of the mantissa.
In the example above, you would again use the row number beginning with .64, but find the column for
2.
In this case, your value is
2. , Once you have these values, the next step is to add them together.
In the example above, you would add 4416 and 2 to get
4418. , The decimal point always goes in a specific designated place: after the number of digits that corresponds to the characteristic plus
1.
In the example above, the characteristic is
2.
You would therefore add 2 and 1 to get 3, then insert the decimal point after 3 digits.
The antilog of
2.6452 is therefore
441.8. -
Step 3: Find the value from the mean difference columns.
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Step 4: Add the values obtained in the previous steps.
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Step 5: Insert the decimal point.
Detailed Guide
Consider the number under observation.
The characteristic is the part that comes before the decimal point; the mantissa is the part that comes after the decimal point.
Antilog tables are arranged with respect to these parameters, so you need to separate them.
As an example, say you need to find the antilog for
2.6452.
The characteristic is 2, and the mantissa is
6452.
Antilog tables are easily available; you may have one in the back of your mathematics textbook.
Open the table and look for the row number consisting of the first two digits of the mantissa.
Then find the column number equal to the third digit of the mantissa.
In the example above, you would open the antilog table and find the row number beginning with .64, then the column for
5.
In this case, you would find that the corresponding value is
4416. , The antilog table also includes a set of columns known as “mean difference columns.” Look at the same row as before (the row corresponding to the first two digits of your mantissa), but this time, find the column number equal to the fourth digit of the mantissa.
In the example above, you would again use the row number beginning with .64, but find the column for
2.
In this case, your value is
2. , Once you have these values, the next step is to add them together.
In the example above, you would add 4416 and 2 to get
4418. , The decimal point always goes in a specific designated place: after the number of digits that corresponds to the characteristic plus
1.
In the example above, the characteristic is
2.
You would therefore add 2 and 1 to get 3, then insert the decimal point after 3 digits.
The antilog of
2.6452 is therefore
441.8.
About the Author
Amy Edwards
Enthusiastic about teaching practical skills techniques through clear, step-by-step guides.
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