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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
= 94

This Question Belongs to Arithmetic Ability >> Permutation And Combination

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Comments ( 2 )

  1. Kumar Chandan
    Kumar Chandan :
    8 years ago

    It is 9 to the power 4 not 94.

  2. Nikhil
    Nikhil :
    8 years ago

    The multiplic of 9*9*9*9=6561 then how it come 94?

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