using System;

using System.Collections.Generic;

using System.Linq;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(IsCurrencyValue("1,000,000 pounds")); // true

        Console.WriteLine(IsCurrencyValue("1,000,000 $"));      // true

        Console.WriteLine(IsCurrencyValue("£1,000,000"));       // true

        Console.WriteLine(IsCurrencyValue("1,000,000"));        // true

        Console.WriteLine(IsCurrencyValue("1,000,000 days"));   // false         

    }

    private static readonly Dictionary<string, CultureInfo> currencies = new()

    {

        {"pound",new CultureInfo("en-GB")}, {"dollar",new CultureInfo("en-US")}, {"euro",new CultureInfo("de-DE")}

        // add more if desired ...

    };

​

    public static bool IsCurrencyValue(string s)

    {

        if(string.IsNullOrWhiteSpace(s)) return false;

        int spaceIndex = s.LastIndexOf(" ");

        string token = spaceIndex == -1 ? null : s.Substring(spaceIndex).Trim();

        if(token?.All(char.IsLetter) == true)

        {

            return currencies.Keys.Any(c => token.StartsWith(c, StringComparison.InvariantCultureIgnoreCase));      

        }

​

        return currencies.Values.Any(culture => decimal.TryParse(s, NumberStyles.Currency, culture, out _));

    }

}