Using scan f in c, write a program to check if the number entered is an even number or old number.
Here is a sample program in C that checks if a number entered by the user is even or odd:
```c
#include <stdio.h>
int main() {
int num;
// Ask user to enter a number
printf("Enter a number: ");
scanf("%d", &num);
// Check if the number is even or odd
if(num % 2 == 0) {
printf("%d is an even number\n", num);
} else {
printf("%d is an odd number\n", num);
}
return 0;
}
```
You can run this program and enter any number, and it will tell you whether the number is even or odd.