How many numbers are there in all from 6000 to 6999 (Both 6000 and 6999 included) having all digits same? 

(a) 216 (b) 356 (c) 496 (d) 504

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1 Answers

(c) Total numbers between 6000 to 6999 = 1000. Now, when all the digits are different, then thousands place is always to be filled by 6, next place by any of the remaining 9 digits and the remaining two places by any of the 8 and 7 digits respectively. So, total no. of numbers, when all digits are different = 9 x 8 x 7 = 504. Hence, total no. of numbers, where all digits are same total numbers — numbers where digits are different 

= 1000 – 504 = 496

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