tonumber

Number tonumber(Text text)
Contexts: computer function, computer program, standard futureprog
Parses text into a number. If parsing fails, the result is 0.
text: The text to parse.

Number tonumber(Text text, Number fallback)
Contexts: computer function, computer program, standard futureprog
Parses text into a number, returning the supplied fallback number when parsing fails.
text: The text to parse.
fallback: The number to return if the text cannot be parsed.