12.
A mobile number consists of ten digits. The first four digits of the number are 9, 8, 8 and 7. The last three digits are 1, 5 and 5. The remaining digits are distinct and make the mobile number, the greatest possible number. What are these digits?
15.
A mobile number consists of ten digits. First four digits are 9,9, 7 and 9. Make the smallest mobile number by using only one digit twice from 7, 2, 5, 8, 0.