Question 252436: the phone numbers in a certain city consist of the prefix 123,234, or 345,followed
by four distinct digits from 0 to 9 how many such phone numbers are possible ?
a 49 b 102 c 5043 d 15120 e 604800
Found 2 solutions by palanisamy, richwmiller:
Answer by palanisamy(496)   (Show Source):
You can put this solution on YOUR website! The phone numbers in a certain city consist of the prefix 123,234, or 345,followed by four distinct digits from 0 to 9
We have to select 4 distinct numbers from 0,1,2,3,4,5,6,7,8,9
Out of 10 numbers 4 can be selected in 10P4 ways
Total number of phone numbers = 10P4
= 10*9*8*7
= 5040
Answer by richwmiller(17219)  (Show Source):
You can put this solution on YOUR website! I believe the answer 5040 provided by the other tutor was for one prefix so you need to multiply by 3 which yields 15120 for the final number which is letter d
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