99 Percentile Qs Bank for JEE MainMathematicsBasics of Mathematics
A three digit number n is such that the last two digits of it are equal and differ from the first. The number of such n 's is
Options
- A64
- B72
- C81
- D900
Correct answer
C. 81
Step-by-step solution
If the last two digits is 0,0 , then in Ist digit any of the numbers except 0 i.e., 9 numbers If the last two digits is 1,1 , then in Ist digit any of the numbers except 0 and 1 , i.e. 8 numbers The total number of numbers =9+8 9=81