using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
		var text = "Top Rate: 8                      88,888 and Top Rate:                       8  \n   88,888";
		var results = Regex.Matches(text, @"\bTop Rate\b.*?(\d(?:[\d,.\s]*\d)?)", RegexOptions.Singleline)
			.Cast<Match>()
			.Select(x => new string(x.Groups[1].Value.Where(c => char.IsDigit(c)).ToArray()));
		foreach (var s in results)
		{
		    Console.WriteLine( s );
		}
	}
}

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