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CSharp · Console

/Program.cs

using System;
using System.Text.RegularExpressions;	

public class Program
{
	public static void Main()
	{
		var original = "this is your sensitive digit 12345 , if you have any question please call +4919003354465";
		var newText = Regex.Replace(original, @"[+]?\d+", Evaluator);
		Console.WriteLine(newText);
		
		string Evaluator(Match match) =>
    		match.Value == "+4919003354465" ? "+4919003354465" : "****";
	}
}