# Probability: theÂ basics

Explore what probability means and why it's useful.

Probability is simply how likely something is to happen.

Whenever weâ€™re unsure about the outcome of an event, we can talk about the probabilities of certain outcomesâ€”how likely they are. The analysis of events governed by probability is called statistics.

**The best example for understanding probability is flipping a coin:**

There are two possible outcomesâ€”heads or tails.

Whatâ€™s the probability of the coin landing on Heads? We can find out using the equationÂ $P(H) = ?$.You might intuitively know that the likelihood is half/half, or 50%. Â But how do we work that out? Â Probability =

In this case:

**Probability of an event = (# of ways it can happen) / (total number of outcomes)**

P(A) = (# of ways A can happen) / (Total number of outcomes)

**Example 1**

There are six different outcomes.

Whatâ€™s the probability of rolling a one?

Whatâ€™s the probability of rolling a one or a six?

Using the formula from above:

Whatâ€™s the probability of rolling an even numberÂ (i.e., rolling a two, four or a six)?

**Tips**

- The probability of an event can only be between 0 and 1Â and can also be written as a percentage.
- The probability of event $A$ is often written as $P(A)$.
- If $P(A) > P(B)$, then event $A$ has a higher chance of occurring than event $B$.
- If $P(A) = P(B)$, then events $A$ and $B$ Â are equally likely to occur.

**Next step:**

Practice basic probability skills on Khan Academy â€”try our stack of practice questions with useful hints and answers!