As I was going to St. Ives
I met a man with seven wives
The seven wives had seven sacks
The seven sacks had seven cats
The seven cats had seven kits
Kits, cats, sacks and wives
How many were going to St. Ives?
One person is going to St. Ives (the narrator). Because the narrator "met" all of the others mentioned in the poem, this implies that they walked past each other in opposite directions, and thus none of the wives, sacks, cats, or kits was actually headed to St. Ives.
If you (like many) think this answer is a bit silly, you can assume that all the people, sacks, and animals mentioned were heading for St. Ives. In this case, we would have 1 narrator + 1 man + 7 wives + 49 sacks + 343 cats + 2401 kits = 2802 total going to St. Ives. However, this isn't the traditional answer.
I drift forever with the current down these long canals they've made.
Tame, yet wild, I run elusive, multitasking to your aid.
Before I came, the world was darker. Colder, sometimes, rougher, true.
But though I might make living easy, I'm good at killing people too.
It can't be seen, can't be felt,
can't be heard and can't be smelt.
It lies behind stars and under hills,
and empty holes it fills.
It comes first and follows after,
ends life and kills laughter.
What is it?