Question

A passcode for a secure website has 6 digits. The first digit cannot be 0. The final 6-digit passcode must be an even number. No digit can be repeated. How many different passcodes are possible?

Answer 1

Okay so consider the first 6 digits be A B C D E F

• A can take values from 1,2,3,4,5,6,7,8,9 - 9 values
• B can take values from 0-9 excluding one value already given for A - 9 values
• C can take 8 values
• D can take 7 values
• E can take 6 values
• F can take 5 values (between 0,2,4,6,8)

Hence the total different passcodes possible = 9*9*8*7*6*5 = 136080 passcodes are possible

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