API tonumber

Attempts to parse the number expressed in a string
 num = tonumber(str[, radix])
==Arguments==
:; str:String/number - this value will be converted to a numeric value.
:; radix: - An optional argument specifies the base to interpret the numeral. The base may be any integer between 2 and 36, inclusive. In bases above 10, the letter `A´ (in either upper or lower case) represents 10, `B´ represents 11, and so forth, with `Z´ representing 35. In base 10 (the default), the number may have a decimal part, as well as an optional exponent part. In other bases, only unsigned integers are accepted.
==Returns==
:; num:Number/nil - The argument as a numeric value or nil if the value cannot be converted.
==Example==
 tonumber("123") -- Returns 123
 tonumber("argqerg") --Returns nil
 tonumber("argqerg", 36) --Returns 4294967295
 tonumber("13", 8) --Returns 11
 tonumber ("D", 16) --Returns 13
==Details==
* This function always converts arg into the native number type.
: If you want to convert from one base to another, you'll have to do the math yourself.
* If base is less than 2 or greater than 36, an error will be thrown ("Base out of range").
* If arg cannot be converted from base to decimal, nil will be returned.