3. What is log? Here we use shortcuts to exponentials for speedy calculations. logarithm of a number to a given base is the power or exponent to which the base must be raised in order to produce that number. For example, the logarithm of 1000 to base 10 is 3 it can be written as : log 10 1000 = 3 usually we use the base of 10, so we can write : log 1000 = 3