The multiplication rule allows us to count the number of possible outcomes for a series of *n* independent events by multiplying the number of options in the first group, the number of options in the second group, and so on. For example, the choices when ordering a pizza may include the size (small, medium, large), the topping (cheese, pepperoni, or veggie) and the crust (thin or deep dish). Thus there are $3*3*2=18$ ways to order a pizza. If you are working at a pizza shop and accidentally make the wrong pizza, the probability that the next pizza ordered will be exactly the same as the one you made incorrectly is 1 in 18.