posted by Camela .
A lock on a bank vault consists of 3 dials, each with 30 positions. In order for the vault to open, each of the three dials must be in the correct position. How many different dial combinations are there for this lock?
Use the multiplication rule if the dial settings are independent of each other.
For example, if we have 4 independent dials each with 5 numbers, then we have 5 choices for each, and multiplication rule gives 5*5*5*5=625 combinations.