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Variables

In this exercise, let's consider how we can use variables and math operators to calculate new values and assign them to a variable. Check out the example below:

```
let x = 4;
x = x + 1;
```

In the example above, we created the variable `x`

with the number `4`

assigned to it. On the following line, `x = x + 1`

increases the value of `x`

from `4`

to `5`

.

Notice, on line two in the example above, to increment `x`

by one we had to write the `x`

variable on the left and right side of the assignment operator (`=`

). Using a variable twice in one expression is redundant and confusing.

To address this, JavaScript has a collection of built-in *mathematical assignment operators* that make it easy to calculate a new value and assign it to the same variable without writing the variable twice. See examples of these operators below.

```
let x = 4;
x += 2; // x equals 6
let y = 4;
y -= 2; // y equals 2
let z = 4;
z *= 2; // z equals 8
let r = 4;
r++; // r equals 5
let t = 4;
t--; // t equals 3
```

In the example above, operators are used to calculate a new value and assign it to the same variable. Let's consider the first three and last two operators separately:

- The first three operators (
`+=`

,`-=`

, and`*=`

) perform the mathematical operation of the first operator (`+`

,`-`

, or`*`

) using the number on the right, then assign the new value to the variable. - The last two operators are the increment (
`++`

) and decrement (`--`

) operators. These operators are responsible for increasing and decreasing a number variable by one, respectively.

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