using the fundamental counting principle with three or more groups of items
There are three highways from city A to city B, two highways from city B to city C,and four highways from city c to city D. How many different highway routes are there from city A to city D?
I see 3*2*4= ?
Those are direct paths. If you allow going back and forth, such as A to b, then B to C, then C to B (on another path), the B to C (on anohter path), well the count increases considerably.