SOLUTION: In a hotel in Hong Kong, a room key is a card. The card has positions for holes that form a 4 by 6 arrays. Each position in the array is either punched with a hole or left blank. H
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-> SOLUTION: In a hotel in Hong Kong, a room key is a card. The card has positions for holes that form a 4 by 6 arrays. Each position in the array is either punched with a hole or left blank. H
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Question 960030: In a hotel in Hong Kong, a room key is a card. The card has positions for holes that form a 4 by 6 arrays. Each position in the array is either punched with a hole or left blank. How many different keys are possible?
The answer is 16777216, but I am not sure what are the steps to solving this. Answer by MathLover1(20849) (Show Source):