# EZ Math Movie, Tutorials, Mathematics, Simple Arithmetic

### Variables

For out purposes, variables in EZ Math Movie work a lot like they do in any math discussion. Here we will confine ourselves to thinking about variables as symbols for values, or as containers for values. Imagine putting numbers into them. Here is a simple statement that assigns a value to a variable:

`x = 5;`

The name of the variable is 'x'. The equal sign could be read: 'is set equal to'. And '5' is the value which is 'placed inside' of x, or which x 'holds', or to which x is 'set'.

Note the semi-colon at the end of the program line.

### Long variable names

In many math subjects variable names are only one letter long. For example, we might use h for the height of a box, as in:

`h = 8;`

But in EZ Math Movie variables can be whole words or phrases, as in these examples:

```height = 8;
boxHeight = 8;
theHeightOfTheBox = 8;```

Digits can appear within a variable name, but not as the first character, as in:

```h2 = 8;
height3 = 8;
box5Height = 8;
```

### The rules for variable names

We will adopt the following naming conventions in EZ Math Movie:

• The first, and perhaps only, character is a letter. After that you can have letters or digits.
• No spaces, punctuation, or other non-letter, non-digit character will be used.

We will usually start the spelling of a variable with a lower case letter. If the variable name is a phrase a few words long, we will capitalize the start of each word within the variable name, as in:

`thisIsAReallyLongVariableName = 3;`

This style of writing variable names is called 'camel case'.

### + - * /

Lets take a look at how to add, subtract, multiply, and divide.

Addition: Uses plus sign, as in 'a equals b plus 3':

`a = b + 3;`

Subtraction: Uses the minus sign, as in 'c equals 4 minus d':

`c = 4 - d;`

Multiplication: Uses the asterisk, as in 'e equals f times 5':

`e = f * 5;`

Division: Use the forward slash, as in 'g equals 6 divided by h':

`g = 6 / h;`

### Precedence

A math expression can contain more than one operation. It could have both an addition and multiplication:

`i = 2 + 3 * 5;`

What happens first, the addition or multiplication? That is a question about math operation precedence. The rules are:

• Multiplication and division happen first.
• Addition and subtraction happen second.
• Evaluation happens inside of parentheses before it happens outside of them.

In the above example 3 times 5 would happen first, evaluating to 15, then the 2 would be added. The variable i would be set to 17.

If we wanted 2 and 3 to be added first, we would need to use parentheses:

`i = (2 + 3) * 5;`

The variable i would be equal to 25, since 2 plus 3 is 5, and 5 times 5 is 25.

### Running the example program

The example program demonstrates how to use a variable; and how to add, subtract, multiply, and divide.

### The example program

0ptions

Go on input

Bounds:
Sorry, apparently this browser does not support HTML 5 canvas tag graphics.
Printer

Edit: Runtime          View: Starter Suggestion

To runtime:

Storage:

Editor width: Normal Wide

### And....

Next tutorial: Random numbers

Here are some links to related articles at EZ Programing Demos:

### Other sites you may find interesting

Like Math and Physics?

Zona Land Education offers explanations, diagrams, and animations on these topics.
And it is all presented in a clear and casual manner.

Want to learn about programing computers?

EZ Programing Demos has an animated, slow motion, interactive programing language demonstrator.
The site presents basic ideas at a beginner's level.

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