Give me some basics on probability in maths

The basic formula for calculating the probability of an event $E$ is:

$$P(E) = \frac{\text{Number of favorable outcomes}}{\text{Total number of possible outcomes}}$$

An outcome is a single result of an experiment, and the sample space is the set of all possible outcomes. An event is a specific collection of outcomes.

For example, if you flip a fair coin, there are two possible outcomes: heads or tails. The probability of getting heads is $\frac{1}{2}$ because there is one favorable outcome (heads) out of two total possible outcomes.