This function converts a number to decimal from any base (up to 16). Its parameters are the number to be converted, and the base to convert from.

integer sbBase2Dec(string strNumber, integer intBase) {
    string  strDigits = "0123456789abcdef";
    integer intDigit  = -llStringLength(strNumber);
    integer intReturn = 0;
 
    while(intDigit)
        intReturn = (intReturn * intBase) + llSubStringIndex(strDigits, llGetSubString(strNumber, intDigit, intDigit++));
    return intReturn;
}