# Math

Sometimes you just need to add a few numbers when you’re working on a task. Nu offers a set of basic math operations that you can use:

To get into “math mode”, you start the command with an `=`. This lets Nu know what you’re about to write will use operators. Some commands, like `where` will do this for you so that you don’t have to.

``````> = 1 + 3
4
``````

In Nu, you can do the usual add, subtract, multiply and divide with the operators `+`, `-`, `*`, and `/` respectively. Operator precedence is respected, so `1 + 2 * 3` will be treated as `1 + (2 * 3)`. Which leads us to parentheses.

## Parentheses

You can use parentheses to group math expression in math mode. This allows you to write `(1 + 2) * 3` if you want the addition to have higher precedence.

## `in:` and `not-in:`

You can check if a value is in a set of values or not using the `in:` and `not-in:` operators.

``````> = 1 in: [1 2 3]
true
``````
``````> = 1 not-in: [1 2 3]
false
``````

## =~ and !~

You can check to see if a string is inside of another string, or not inside of another string, using `=~` and `!~`.

``````> = "foobar" =~ "foo"
true
``````
``````> = "foobar" !~ "baz"
true
``````

## Comparisons

The following comparisons are also available:

• `<` - less than
• `<=` - less than or equal to
• `>` - greater than
• `>=` - greater than or equal to
• `==` - equal to
• `!=` - not equal to

## Compound operators

Nushell also supports `&&` and `||` to join two operations that return boolean values, using ‘and’ and ‘or’ respectively. For example: `ls | where name in: ["one" "two" "three"] && size > 10kb`