using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
		var strs = new List<string> { "7","7,5","7.5","7,5 This is my string","7.5 Hello","7,75","11","7This is my string","7.This is my string","10.5 string"};
    	var pattern = @"^(?:10|[1-9](?:[.,][0-9])?)(?:\s.*)?$";
        foreach (var s in strs)
        	if (Regex.IsMatch(s, pattern))
        		Console.WriteLine("{0} is correct.", s);
        	else
        		Console.WriteLine("{0} is invalid.", s);
	}
}

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