These procedures allow the creation and processing of numerals using any set of Unicode digits.
(number->numeral z zero)
(numeral->number string zero)
It is an error if zero is not a character whose Unicode general category is Nd (decimal digit) and whose numeric value is zero.
These procedures behave identically to number->string and string->number from the (scheme base) library, except that where number->string generates and string->number accepts a 0 character, these procedures generate and accept a character equal to zero. Similarly, the successor of zero is generated and accepted in place of 1, the successor of the successor of zero is generated and accepted in place of 2, and so on. Note that the radix is always decimal.