【Answer】Solution: After reversing the digits: $27-2=25$, the result after multiplying by 2 is: 52, the original number is: $52 \div 2=26$; Answer: The number initially entered is 26. Therefore, the answer is: 26.
5. (10 points) There is a special calculator. When a number is input, the calculator multiplies this number by 2, then reverses the order of the digits of the result. After adding 2, it displays the final result. If a two-digit number is input, and the final result displayed is 27, then the number initially input was . $\qquad$