How to distinguish whether a variable is a pure numeric string or a number, such as "123" and "123".

HI Guys.

I want to know how to distinguish whether a variable is a pure numeric string or a number, such as "123" and "123".

I only know an inelegant way.

ClassMethod IsNumber(n)
{
	s ret=0
	try{
		s ret= $lb(n)=$lb(+n)
	}catch e{
		s ret=0
	}
	q ret
}

Is there any other way to implement it