C Exercises: Find the n^th digit of number 1 to n

C Programming Mathematics: Exercise-17 with Solution

Write a C program to find the nth digit of the number 1 to n?
Infinite integer sequence: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 .. where n is a positive integer.

Example:
Input:
7
Output:
7
Input:
12
Output:
1
The 12th digit of the sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ... is 1, which is part of the number 11.

Pictorial Presentation:

Sample Solution:

C Code:

#include <stdio.h>

int find_Nth_Digit(int n) {
    unsigned int i, j, k;
    i = j = 1;
    while (n > 9 * i * j) {
        n -= 9 * i * j;
        j *= 10;
        i ++;
    }
    k = j + (n - 1) / i;
    for (j = (n - 1) % i; j < i - 1; j ++) {
        k = k / 10;
    }
    return k % 10;
}

int main(void)
{
  int n = 7;
  printf("\n%d digit of the sequence is %d",n,find_Nth_Digit(n));
  n = 12;
  printf("\n%d digit of the sequence is %d",n,find_Nth_Digit(n));
  return 0;    
}

Sample Output:

7 digit of the sequence is 7
12 digit of the sequence is 1

Flowchart:

C Programming Code Editor:

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