Bunuel wrote:
How many times will the digit 7 be written when listing the integers from 1 to 1000?
A. 110
B. 111
C. 271
D. 300
E. 304
Here is how I worked out:
07,17,27,37,47,57,67,70,71,72,73,74,75,76,77,78,79,87,97 ---> 20 times.
Now we will have this pattern for 0-100,100-200,200-300 till 900-1000. Ignore the 700s for now. So we have 20*9 =180 times. So C/D/E.
Let's focus on 700s now. 700,701,702,703,704....799. That's 100 times. Ignore the 77X for now. So 180+100= 280. We are down to D or E.
Let's try 77X now. 770,771,772...779. We have counted the 7 at hundred's place. So we need to add 11 more. 280+11=291.
At this point I marked Option D.
But the missing 7s are: 707,717,727,737,747,757,767,787,797. (The 7's at units place) (Took me a while to figure this out
)
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