Pip writes down a four-digit number. In Pip\textquotesingle s number, the thousands digit is same as the units digit. Bud reverses the units digit and the tens digit of it and gets a new number. Pip\textquotesingle s number and Bud\textquotesingle s number add up to $5510$. What is Pip\textquotesingle s number? 
Overseas Competition->Knowledge Point->Combinatorics->Number Puzzles