SOLUTION: How many different two-digit numbers can be formed using the digits 1, 3, 4, and 5. Repetition of digits is allowed.
How many 7-digit phone numbers can be formed if the first
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Question 84121: How many different two-digit numbers can be formed using the digits 1, 3, 4, and 5. Repetition of digits is allowed.
How many 7-digit phone numbers can be formed if the first digit cannot be 0 and repetition of digits is allowed?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
How many different two-digit numbers can be formed using the digits 1, 3, 4, and 5. Repetition of digits is allowed.
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4*4 = 16 two-digit numbers
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How many 7-digit phone numbers can be formed if the first digit cannot be 0 and repetition of digits is allowed?
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ways to choose the first digit = 9
ways to choose remaining 6 digits = 10^6
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Total number of 7-digit phone numbers = 9*10^6 = 9 million
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Cheers,
Stan H.
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