25. The room numbers of a hotel are all three-digit numbers. The first digit represents the floor and the last two digits represent the room number. The hotel has rooms on five floors, numbered 1 to 5 . It has 35 rooms on each floor, numbered $\mathrm{n} 01$ to $\mathrm{n} 35$ where $\mathrm{n}$ is the number of the floor. In numbering all the rooms, how many times will the digit 2 be used?
A 60
В 65
C 95
D 100
E 105
25. E Each floor has 35 rooms. On every floor except floor 2 , the digit 2 will be used for rooms ' $n 02$ ', ' $n 12$ ', ' $n 20$ ' to ' $n 29$ ' (including ' $n 22$ ') and ' $n 32$ '. Hence the digit 2 will be used 14 times on each floor except floor 2 . On floor 2, the digit 2 will be used an extra 35 times as the first digit of the room number. Therefore the total number of times the digit 2 will be used is $5 \times 14+35=105$.