To evaluate the common logarithm of a number can be seen as finding what exponent the number must be raised to in order to get that number. Here, we take the logarithm of the number We already know that we raise to to get that number. Therefore, we can evaluate the logarithm immediately. We can just read what the exponent is in the argument of the function. This is always true when evaluating the common logarithm of a power with the base
The same reasoning applies here. The number is accuired by raising to
Here we need to rewrite the number as a power of ten. The logarithm will then be determined as in the previous calculations.