Number=5
Inside quotation of printf() there, is a conversion format string "%d" (for integer). If this conversion format string matches with remaining argument,i.e, c in this case, value of c is displayed.
#include<stdio.h>
int main()
{
int c;
printf("Enter a number\n");
scanf("%d",&c);
printf("Number=%d",c);
return 0;
}