# NaN and NA

> For the complete documentation index, see [llms.txt](https://kotlin.github.io/dataframe/llms.txt).

Using the Kotlin DataFrame library, you might come across the terms `NaN` and `NA`. This page explains what they mean and how to work with them.

## NaN

`Float` or `Double` values can be represented as `NaN`, in cases where a mathematical operation is undefined, such as for dividing by zero. The result of such an operation can only be described as "Not a Number".

This is different from `null`, which means that a value is missing and, in Kotlin, can only occur for `Float?` and `Double?` types.

You can use [fillNaNs](fill.html#fillnans) to replace `NaNs` in certain columns with a given value or expression or [dropNaNs](drop.html#dropnans) to drop rows with `NaNs` in them.

## NA

`NA` in DataFrame can be seen as: [NaN](#nan) or `null`. Which is another way to say that the value is "Not Available".

You can use [fillNA](fill.html#fillna) to replace `NAs` in certain columns with a given value or expression or [dropNA](drop.html#dropna) to drop rows with `NAs` in them.