# `Cldr.UnknownNumberSystemTypeError`
[🔗](https://github.com/elixir-cldr/cldr/blob/v2.47.4/lib/cldr/exception.ex#L36)

Exception raised when an attempt is made to use a number system type that is not known
in `Cldr`.  `Cldr.Number.number_system_types/0` returns the number system types known to `Cldr`.

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*Consult [api-reference.md](api-reference.md) for complete listing*