S = a string value
HEXTONUM returns the numeric value for the hexadecimal (base 16) interpretation of S. Since SpreadScript can operate directly on hexadecimal numbers, this function is not very useful; it is included primarily to maintain compatibility with other spreadsheets.
HEXTONUM(``A'') = 10
HEXTONUM(J10) = 45019, where J10 = ``AFDB''
Excel function: N/A