3.fibonacci series:

/* Displaying Fibonacci series up to certain number entered by user. */

#include <stdio.h>
 main()
{
  int t1=0, t2=1, display=0, num;
  printf("Enter an integer: ");
  scanf("%d",&num);
  printf("Fibonacci Series: %d+%d+", t1, t2); /* Displaying first two terms */
  display=t1+t2;
  for(display=t1+t2;display<num; display=t1+t2;)  {
      printf("%d+",display);
      t1=t2;
      t2=display;
     
  }
  
}

Output

Enter an integer: 200
Fibonacci Series: 0+1+1+2+3+5+8+13+21+34+55+89+144+