using System;

using System.Collections.Generic;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        var text = new List<string>

        {

            "coins",

            "coins_multiplier_x1",

            "coins_multiplier_x2",

            "coins_multiplier_x3",

            "__multiplier_x3",

            "coins_multiplier_x_",

            "easy_three",

            "easy_three_multiplier_x3",

        };

        foreach(var row in text)

        {

            GetRewardName(row);

        }

    }

    private static string GetRewardName(string rewardType)

    {

        var regex = new Regex(@"(?<name>\w+)_multiplier_x(?<multiplier>\d+)", RegexOptions.Compiled | RegexOptions.IgnoreCase);

        var match = regex.Match(rewardType);

​

        if (!match.Success)

        {

            Console.WriteLine("No matches");    

            return rewardType;

        }

​

        var name = match.Groups["name"].Value;

        var multiplier = match.Groups["multiplier"].Value;

​

        Console.WriteLine("Found Match for {0}", match.Value);

        Console.WriteLine("multiplier was {0}", match.Groups["multiplier"].Value);

        Console.WriteLine("name was {0}", match.Groups["name"].Value);

        return name;

    }

}