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Q.

How many different telephone numbers are there if it is assumed that each number contains not more than seven digits (the first digit is not allowed to be 0 or 1 in a telephone number)?


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a

4 million

b

8 million

c

3 million

d

1 million 

answer is B.

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Detailed Solution

Since, first digit is not allowed to be 0 or 1.
The selection of remaining 6-digit number is done from = (000000 to999999)
After counting, possible numbers are  106 (1 million)
 Possibilities of first number= 8
 Total possibilities = 8×106 (8 million).
Correct option is 2.
 
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