From the definition of logarithms, you can get two relationships that are quite useful. They can be interpreted as a "common logarithm of" and "ten raised to the power of" cancelling each other out.
If a logarithm, is an exponent to , you can directly determine the power of ten value by reading of the logarithms argument,
You can only calculate logarithms of positive numbers. There's no number that you can raise 10 to in order to get zero or a negative result. As a result, this identity applies only when
If you take a logarithm of a power of ten, the result is the exponent. This is the most practical interpretation of the definition of the base-10 logarithms.