using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		var packageSize = "4/8.75LB";
		//var packageSize = "LB"; // => 'LB' did not match the regex.
    	var result = Regex.Split(packageSize, @"(\d)(?=\D*$)");
    	if (result.GetLength(0) != 1) { // We have found a match
        	foreach (var s in result)
	        	Console.WriteLine(s);
    	}
    	else
    	{
    		Console.WriteLine($"'{packageSize}' did not match the regex.");
    	}
	}
}