Understand what a logarithm is. 102 is 100. 103 is 1000. The powers 2 and 3 are the base-10 logarithms of 100 and 1000.[1] In general, ab = c can be rewritten as logac = b. So, saying "ten to the power of two is 100" is equivalent to saying "the base-ten log of 100 is two." Each logarithmic table is only usable with a certain base (a in the equation above). By far the most common type of log table uses base-10 logs, also called the common logarithm.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.
