Answer L10

#include <stdio.h>
#include <stdlib.h>

/* Puzzle L10 -- print the integers from 0 to 24, five per line */
int main()
{
  int j;
  for (j=0; j<25; j++ )
  {
    printf("%3d", j);
    if ( j%5==4 ) printf("\n");
  }

  return 0;
}

Comments:

The problem is to print "\n" after every group of five integers. So, determine which integers end each group. These are 4, 9, 14, 19, and 24. All these integers yield a remainder of 4 when divided by 5.