Why do we have to tell printf() the type of data in C?

Let's consider this C code:

#include <stdio.h>

main()
{
  int x=5;
  printf("x is ");
  printf("%d",5);
}

In this, when we wrote int x=5; we told the computer that x is an integer. The computer must remember that x is an integer. But when we output the value of x in printf() we have to again tell the computer that x is an integer. Why is that?

Why does the computer forget that x was an integer?