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Question
How many 3-digit numbers can be formed by using the digits 1 to 9 if no digit is repeated?
Solution
Total number of arrangements of 9 digits, taken 3 at a time = 9P3
∴ Total 3-digit numbers that can be formed by using the digits 1 to 9, if no digit is repeated = 9P3 = `9xx8xx7=504`
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