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 = 94This Question Belongs to Arithmetic Ability >> Permutation And Combination
It is 9 to the power 4 not 94.
The multiplic of 9*9*9*9=6561 then how it come 94?