An audio decoder (200;800) for providing a decoded audio information (212;812) on the basis of an encoded audio information (210;810), the audio decoder comprising: an arithmetic decoder (230;820) for providing a plurality of decoded spectral values (232;822) on the basis of an arithmetically-encoded representation (222;821) of the spectral values comprised in the encoded audio information; and a frequency-domain-to-time-domain converter (260;830) for providing a time-domain audio representation (262;812) using the decoded spectral values (232;822), in order to obtain the decoded audio information (212;812); wherein the arithmetic decoder (230;820) is configured to select a mapping rule (297;cum_freq[]) describing a mapping of a code value (value) of the arithmetically-encoded representation (222;821) of spectral values onto a symbol code (symbol) representing one or more of the decoded spectral values or at least a portion of one or more of the decoded spectral values in dependence on a context state described by a numeric current context value (c); and wherein the arithmetic decoder (230;820) is configured to determine the numeric current context value (c) in dependence on a numeric previous context value and in dependence on a plurality of previously-decoded spectral values, wherein the arithmetic decoder is configured to modify a number representation of the numeric previous context value, describing a context state for the decoding of one or more previously decoded spectral values, in dependence on a context subregion value describing a subregion of a context, to obtain a number representation of a numeric current context value describing a context state for the decoding of one or more spectral values to be decoded. an arithmetic decoder (230;820) for providing a plurality of decoded spectral values (232;822) on the basis of an arithmetically-encoded representation (222;821) of the spectral values comprised in the encoded audio information; and a frequency-domain-to-time-domain converter (260;830) for providing a time-domain audio representation (262;812) using the decoded spectral values (232;822), in order to obtain the decoded audio information (212;812); wherein the arithmetic decoder (230;820) is configured to select a mapping rule (297;cum_freq[]) describing a mapping of a code value (value) of the arithmetically-encoded representation (222;821) of spectral values onto a symbol code (symbol) representing one or more of the decoded spectral values or at least a portion of one or more of the decoded spectral values in dependence on a context state described by a numeric current context value (c); and wherein the arithmetic decoder (230;820) is configured to determine the numeric current context value (c) in dependence on a numeric previous context value and in dependence on a plurality of previously-decoded spectral values, wherein the arithmetic decoder is configured to modify a number representation of the numeric previous context value, describing a context state for the decoding of one or more previously decoded spectral values, in dependence on a context subregion value describing a subregion of a context, to obtain a number representation of a numeric current context value describing a context state for the decoding of one or more spectral values to be decoded.