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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?

A) 120
B) 100000
C) 6720
D) 30240

Correct Answer:



C) 6720

Description for Correct answer:
There is a 7-digit telephone number but extreme right and extreme left positions are fixed

ie.., 6 x x x x x 5

So the required number of ways = 8 x 7 x 6 x 5 x 4 = 6720

Part of solved Permutation and combination questions and answers : >> Aptitude >> Permutation and combination

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