# Complementary Probability

**Formula:**`P(A') = 1 - P(A)`

## Introduction to Complementary Probability

The concept of complementary probability refers to the probability of the complement of an event. Essentially, if you have a certain event, A, with a probability P(A), the complement of A (denoted as A') is the event that A does not occur. The probability of A' is simply 1 minus the probability of A.

## Parameter usage:

`probabilityA`

= probability of the occurrence of event A

## Output:

`complementaryProbability`

= probability of the event A not occurring

## Data validation

The probability should be a valid number between 0 and 1.

## Practical applications

Understanding complementary probability is crucial in many fields, including statistics, gaming, insurance, and risk assessment, as it allows one to calculate the likelihood of an event not happening based on the likelihood of it happening.

Tags: Probability, Complement, Mathematics