Hello Fatemeh,

Thank you for posting in our forums!

I have tried to reproduce your issue on my side, and I am not sure that I am seeing issue here. I’ve tested Infragistics UltraTextEditor and standard MS TextBox and both components works on the same way. When you type successively “الف12345” the result you expect “12345الف”. The numbers are not in the opposite order of the typing, since they are in decimal notation, which meant that the position of the digit determines the value, changing the order of the digits in the number changes its value. So if this is the issue, it is expected behavior. 

Please let me know if you have any further questions or if I misunderstood you.