Probability is the numerical measure of the chance of an outcome or event occurring. When all outcomes are equally likely to occur, the probability of the occurrence of a given outcome can be found by using the following formula:

probability = number of favorable outcomes/number of possible outcomes

Example 1: What is the probability that on two consecutive rolls of a die the numbers will be 2 and then 3? (A die has sides numbered 1-6).

Since the probability of getting a 2 on the first roll is 1/6 and the probability of getting a 3 on the second roll is 1/6, and since the rolls are independent of each other, simply multiply.

1/6 x 1/6 = 1/36

Example 2: What is the probability of tossing heads three consecutive times with a two-sided fair coin?

Because each toss is independent and the odds are 1/2 for each toss, the probability is

1/2 x 1/2 x 1/2 = 1/8