# Convert a Positive Number to Negative in JavaScript

Fri Oct 22 20212 min read

Photo by Joshua Newton

## Convert a Positive Number to Negative#

To convert a positive number to a negative number, prefix a call to the `Math.abs()` method with a minus, e.g. `-Math.abs(10)`. When prefixed with a minus, the `Math.abs` method will always return a negative number.

index.js
```Copied!```console.log(-Math.abs(10)); // ๐๏ธ -10
console.log(-Math.abs(10.5)); // ๐๏ธ -10.5
console.log(-Math.abs(-10)); // ๐๏ธ -10
``````

We used the Math.abs method to convert positive to a negative numbers.

The only parameter the method takes is the number we want to get the absolute value of.

The method returns the absolute value of a number, in other words it returns the number's distance from zero.

Here are some examples.

index.js
```Copied!```console.log(Math.abs(-5)); // ๐๏ธ 5
console.log(Math.abs(5)); // ๐๏ธ 5
console.log(Math.abs('5')); // ๐๏ธ 5
``````

The `Math.abs` method returns the provided number if it's positive or zero and the negation of the number if it's negative.

By default the method always returns a positive number, so by prefixing it with a minus `-`, we are guaranteed to get a negative number back.

An alternative approach is to use multiply by `-1`.

To convert a positive number to a negative number, multiply the number by `-1`, e.g. `5 * -1`. By multiplying the number by `-1`, we flip the number's sign and get back a negative number.

index.js
```Copied!```console.log(10 * -1); // ๐๏ธ -10
console.log(10.5 * -1); // ๐๏ธ -10.5
console.log(-10 * -1); // ๐๏ธ 10
``````
Notice however that our third example is different from when we used the `Math.abs` method. We multiplied a negative number by `-1` and got back a positive number.

By multiplying a number by `-1`, we just flip its sign.

To avoid this scenario, use the `Math.abs` method prefixed with a minus. This guarantees you that even if a negative number is provided, a negative number will be returned.