# What is a Function in Math? - Definition & Examples

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• 0:04 Function: Definition
• 0:58 Functions in Math
• 1:28 More Examples
• 1:53 Lesson Summary

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Lesson Transcript
Instructor: Allison Petrovic

Allison has experience teaching high school and college mathematics and has a master's degree in mathematics education.

Have you ever gotten candy out of a vending machine? Getting candy from a vending machine is similar to using a function in math! In this lesson, we'll explore the definition of a function and some examples.

## Function: Definition

Whenever you buy something from a vending machine, what do you usually get? Maybe a bag of Sun Chips or a Twix candy bar? When choosing your purchase, have you ever stopped to think about how a vending machine works? First, you put in your money. Then, you press the button associated with the item you want. Lastly, you receive your treat and eat it. A commercial vending machine operates in much the same way as a mathematical function.

A function is one or more rules that are applied to an input and yield an output. The input is the number or value put into a function. The output is the number or value the function gives out. Let's see what these definitions mean using our vending machine example.

The money we insert into the vending machine in the input. The buttons we press on the vending machine represent the function. The bag of Sun Chips or Twix candy bar we receive in return is our output.

## Functions in Math

Now, let's talk about functions in math using an example:

In this example, our input is 5. The function is to add 3 to 5. As 5 + 3 = 8, 8 is our output.

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