MHB 1000 th Digit in a Given number N

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To find the 1000th digit of the large integer N formed by writing all multiples of 6 side-by-side, one must first understand the sequence of these multiples. The digits of N are generated from the concatenation of numbers like 6, 12, 18, 24, and so on. Calculating the total number of digits contributed by each multiple helps in pinpointing the exact location of the 1000th digit. By systematically counting the digits from the beginning of the sequence, the 1000th digit can be identified accurately. The process involves careful tracking of the cumulative digit count as more multiples are added.
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If all the multiples of 6 are written side-by-side, then a large integer $N$ is generated as follows:

$N=61218243036\ldots$ ,Then the question is to find the $1000$th digit of $N$.
 
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jacks said:
If all the multiples of 6 are written side-by-side, then a large integer $N$ is generated as follows:

$N=61218243036\ldots$ ,Then the question is to find the $1000$th digit of $N$.

we need to take n digit numbers starting from 1 = 1 on wards

there is 1 one digit number multiple of 6
so remaining digits = 999
then there are 15 ( 6 * 2 to 6 * 16) 2 digit numbers which is 30

so remaining number of digits = 969

there are 150 (6 * 17 to 6 * 166) 3 digit numbers and they take 450 digit and so remaining digits = 519

now there are much more 4 digit numbers multiple of 6 and for 516 digits we require 130 numbers and as 520 = 130 * 4 = 519 + 3 so it is tens digit digit.

now 1st 4 digit number = 1002 and so 130th 4 digit number = 1002 + 129 * 6 = 1002 + 774
= 1776
required digit is 7
 
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