There is a 7-digit telephone number with all different digits. if the digit at extreme right and extreme left are 5 and 6 respectively, find how many such telephone numbers are possible?
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37
Solution :-
If the digits at extreme right and extreme left are 5 and 6 respectively.
So, the the 7 digit telephone number will be - 6_ _ _ _ _ 5
The second digit can be chosen from 8 (i.e. 0, 1, 2, 3, 4, 7, 8 and 9) of the remaining digits.
There 5 spaces left in the above number.
So, total number of possible telephone numbers will be = 8P5
= 8!/3!
= 6720
Answer.
If the digits at extreme right and extreme left are 5 and 6 respectively.
So, the the 7 digit telephone number will be - 6_ _ _ _ _ 5
The second digit can be chosen from 8 (i.e. 0, 1, 2, 3, 4, 7, 8 and 9) of the remaining digits.
There 5 spaces left in the above number.
So, total number of possible telephone numbers will be = 8P5
= 8!/3!
= 6720
Answer.
Answered by
10
On the off chance that the digits at outrageous right and extraordinary left are 5 and 6 individually.
In this way, the 7 digit phone number will be 6 to 5
The second digit can be looked over 8 of the rest of the digits.so the five spaces will left. Along these lines, add up to number of conceivable phone numbers will be = 8 P 5 then= 8/3 so the answer will be our 6720 .
In this way, the 7 digit phone number will be 6 to 5
The second digit can be looked over 8 of the rest of the digits.so the five spaces will left. Along these lines, add up to number of conceivable phone numbers will be = 8 P 5 then= 8/3 so the answer will be our 6720 .
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