NUMBER - convert string to a number.

NUMber(S1 [,I1]) returns N, or S

interprets string S1 as a number in base I1. I1 is zero or omitted, NUMber chooses the base by the form of the number; a leading zero indicates octal and no leading zero indicates decimal. If I1 is -1, the number is read as floating point. If S1 cannot be interpreted as a number, NUMber returns the string unchanged. Thus, the expression "type(number(s))" determines if "s" is a valid number.