Making large constants in C source more readable?

Question

I\'m working on some code for a microprocessor.
It has a few large, critical constants.

#define F_CPU 16000000UL

In this case, this is the C

Answer 1

maybe something like that?

#define MHz(x) (1000000 * (x))
...
#define F_CPU MHz(16)

Also, I don't like #defines. Usually it's better to have enums or constants:

static const long MHz = 1000*1000;
static const long F_CPU = 16 * MHz;