---
title: notANumber
framework: foundation
role: symbol
role_heading: Type Property
path: foundation/nsdecimalnumber/notanumber
---

# notANumber

A decimal number that specifies no number.

## Declaration

```swift
@NSCopying class var notANumber: NSDecimalNumber { get }
```

## Return Value

Return Value An NSDecimalNumber object that specifies no number.

## Discussion

Discussion Any arithmetic method receiving notANumber as an argument returns notANumber. This value can be a useful way of handling non-numeric data in an input file. This method can also be a useful response to calculation errors. For more information on calculation errors, see the exceptionDuringOperation(_:error:leftOperand:rightOperand:) method description in the NSDecimalNumberBehaviors protocol specification.

## See Also

### Creating a Decimal Number

- [one](foundation/nsdecimalnumber/one.md)
- [zero](foundation/nsdecimalnumber/zero.md)