SOLUTION: How many four digit number can be formed by using digits 1,3,5,7,7,8 and 9 (No digit should be repeated)?

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Question 1167894: How many four digit number can be formed by using digits 1,3,5,7,7,8 and 9 (No digit should be repeated)?
Answer by greenestamps(13198) About Me  (Show Source):
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The digits can't be repeated, so having the second 7 in the list of available digits is a confusion factor that should be ignored.

There are 6 different digits; you need to make a 4-digit number using four of them.

6 choices for the first;
5 choices for the second;
4 for the third; and
3 for the fourth.

By the fundamental counting principle, the total number of 4-digit numbers possible is the product of the numbers of ways to choose each digit.

ANSWER: 6P4 = 6*5*4*3 = 360