Example: log10(31. 62) requires a base-10 table.
Row labeled with first two digits of n Column header with third digit of n Example: log10(31. 62) → row 31, column 6 → cell value 0. 4997.
Stay in same row Find small column header with fourth digit of n Add this to previous value Example: log10(31. 62) → row 31, small column 2 → cell value 2 → 4997 + 2 = 4999.
Example: Solution so far is ?. 4999
Example: 101=10<31. 62{\displaystyle 10^{1}=10<31. 62} and 102=100>31. 62{\displaystyle 10^{2}=100>31. 62}. The “characteristic” is 1. The final answer is 1. 4999 Note how easy this is for base-10 logs. Just count the digits left of the decimal and subtract one.
Multiply two numbers by adding their powers. For example: 102 * 103 = 105, or 100 * 1000 = 100,000. The natural log, represented by “ln”, is the base-e log, where e is the constant 2. 718. This is a useful number in many areas of math and physics. You can use natural log tables in the same way that you use common, or base-10, log tables.
Sometimes the numbers in this row will have a decimal point, so you’ll look up 2. 5 rather than 25. You can ignore this decimal point, as it won’t affect your answer. Also ignore any decimal points in the number whose logarithm you’re looking up, as the mantissa for the log of 1. 527 is no different from that of the log of 152. 7.
The anti-log is also commonly known as the inverse log.
