An unfortunate thief was caught while trying to decode the 3-digit numerical code of a lock. The Police caught him while

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An unfortunate thief was caught while trying to decode the 3-digit numerical code of a lock. The Police caught him while he was making the second-last possible unique attempt. How many attempts did the thief make in total?

A. 5
B. 26
C. 719
D. 999
E. 1000

Answer: D

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- The thief was trying to decode a 3-digit code
- He was caught on the second to the last attempt


A single-digit could be any of 0,1,2,3.4,5,6,7,8 or 9 which happens to be10 different numbers
Therefore, total possible codes = 10^n where n = number of digits
Total possible codes = 10^3 = 10 * 10 * 10 = 1000


Since he was caught in the second to the last possible attempt
Total number of previous attempt = 1000 - `1
= 999

Answer = D

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