The answer is 5. Choice D. Solutions can be found here ->
12-days-of-christmas-gmat-competition-day-3-if-k-is-the-number-form-439152.htmlThat said, here is one way to think about the problem ->
-> 1 to 9 -> 9 digits
-> 10 to 99 -> 90 numbers -> 90x2 = 180 digits
-> So, single digit and 2-digit numbers account for 180+9 = first 189 digits of k.
-> 3-digit numbers -> 100 to 999 -> 900 numbers -> 900 x 3 = 2700 digits. We need only the 341st digit ---> So, we can infer that the 341st digit is from a 3-digit number. But which one?
-> Ask. We already have 189 digits. How many more digits till 341? 341 - 189 = 152.
-> This is 50 numbers -> 50 x 3 = 150 digits + another 2 digits for the 341st.
-> 100 to 149 -> 50 numbers, 150 digits.
-> The next num is 150. We need only the 2nd digit - "5". This is the 341st digit of k.