A letter lock consists of 4 rings, each ring contains 9 non-zero digits. This lock can be opened by setting four digit code with the proper combination of each of the 4 rings. Maximum how many codes can be formed to open the lock ?
A. 49
B. 94
C. 9P4
D. None of these
Answer: Option B
Solution(By Examveda Team)
There are 9 non-zero digits to arrange themselves at 4 different position. Each letter can be arrange at different position in 9 different ways. So, required number of ways, = 9 × 9 × 9 × 9 = 94Join The Discussion
Comments ( 2 )
Related Questions on Permutation and Combination
A. 3! 4! 8! 4!
B. 3! 8!
C. 4! 4!
D. 8! 4! 4!
A. 7560,60,1680
B. 7890,120,650
C. 7650,200,4444
D. None of these
A. 8 × 9!
B. 8 × 8!
C. 7 × 9!
D. 9 × 8!
It is 9 to the power 4 not 94.
The multiplic of 9*9*9*9=6561 then how it come 94?