Sometimes a logarithm is written withouta base, like this: log(100) This usually means that the base is really 10. It is called a "common logarithm". Engineers love to use it. On a cal… See more

Another base that is often used is e (Euler's Number)which is about 2.71828. This is called a "natural logarithm". Mathematicians use this one a lot. On a calculator i… See more

Mathematicians may use "log" (instead of "ln") to mean the natural logarithm. This can lead to confusion: So, be careful when you read "log" that you know what base they mean!… See more

All of our examples have used whole number logarithms (like 2 or 3), but logarithms can have decimal values like 2.5, or 6.081, etc. Read Logarithms Can Have Deci… See more

Multiplying and Dividing are all part of the same simple pattern. Let us look at some Base-10 logarithms as an example: Looking at that table, see how positive, zero or negative lo… See more