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The Number of times the digit 8 will be written when listing the integers from 1 to 1000 is :

Correct Answer: 300

Explanation:

 Since 8 does not occur in 1000, we have to count the number of times 8 occurs when we list the integers from 1 to 999. Any number between 1 and 999 is of the form xyz, where  0 x , y , z 9 .


 


Let us first count the numbers in which 8 occurs exactly once.


 


Since 8 can occur atone place in  3 C 1 ways. There are  3   x   9   x   9    such numbers.


 


Next, 8 can occur in exactly two places in  3 C 2 × 9  such numbers. Lastly, 8 can occur in all three digits in one number only.


  


Hence, the number of times 8 occur is 


  1 × 3 × 9 2 + 2 × 3 × 9 + 3 × 1   =   300


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