1.

A letter lock consists of 4 rings, each ring contains 9 non-zero digits. This lock can be opened by setting a 4 digit code with the proper combination of each of the 4 rings. Maximum howmany codes can be formed to open the lock?

Answer»

`4^9`
`""^(9)P_4`
`9^4`
NONE of these

Answer :C


Discussion

No Comment Found