1 'hole' if you can call it that. Imagine if the straw started life as a solid cylinder and you had to bore out the inside to turn it into a straw: if that were the case, you would drill 1 hole all the way through it.

Another analogy is a donut. Would you agree that a donut has just 1 hole? I would say yes. Now stretch that donut vertically untill you have a giant cylinder with a hole in the middle. That's basically now just a straw. The fact you stretched it doesn't increase the number of holes it has.

How many holes does a donut have?

Now make the donut higher. A lot higher. Now you have a donut-tunnel. Now make the walls thinner. Now shrink it. Now you have a straw.

One hole.

How many holes does a rubber band have? A donut?

Topologically a rubber band, a donut, and a straw have the same number of holes. The hole at either end of the straw is just a continuation of the same one hole.

Classic topology question. Absolutely one hole; it goes all the way through.

Of course, connotatively, two is a fine assessment, but not in topology.

How many holes does a donut have? Now just try to image the real difference between a straw and a donut. Is there one, aside from deliciousness?

Mathematically It's one. Think of a disk, like a CD, does it have one hole or two? One, right? Now imagine you can make it thicker, I.e. increase the height, and then reduce the outer radius... Making it progressively more straw-like. At what point does it stop having 1 hole and begin to have 2?

Topologically they're the same shape.

I'm sure Matt Parker has a video on this topic in YouTube. Here

how many holes does a donut have? one. a straw is just a tall plastic donut.

two holes... smdh... kids these days

A straw is geometrically the same as a circular piece of paper with a z depth of zero and a hole in the middle. Because the z depth is zero there is only one hole. As you add thickness the one hole remains. Therefore, a straw has one hole.

Does a doughnut have two holes?

Because a straw is just an elongated doughnut.

It has two exits, one hole.

If you drill a hole in a block of wood you create one hole not two, note that whether or not the drill exits the opposite side, only one hole has been created despite differing numbers of exits.

It's just one long hole.

The answer depends on the context. Topologically, it's one. I personally like zero. If I say "There's a hole in my straw!" You'll not think all straws have holes. You'll think there's something wrong with it.

It's one, big long hole. If you drilled a hole through a board, do you say it's two holes?

Or it's 0 holes, as it's not cut out of something, but rather just formed that way meaning by strict dictionary definition, there are no "holes."

I believe the confusion lies in the word "holes" when you are thinking about openings or exits. Just my 2 cents.

One of course, what a weird conversation to have.

If you make the straw less long, it’s a donut. And a donut obviously has 1 hole. So a long donut only has one hole. Q.E.D

To settle this argument could you clarify if we're supposed to be considering the straw as a solid 3D object with a thickness, or as a curved 2D surface? The answer kind of depends on which you pick.

A hollow cylinder has a single hole, with two openings. A hole can be open on one end only (e.g., a well is a hole in the ground), or it can have multiple openings (e.g., a straw has a hole with two openings).

If one cannot immediately tell whether two openings are connected to one another, then one assumes they are not; e.g., if you see a well in Florida you don't assume it is the opening of a hole that extends to connect to another opening in Australia.

one hole is going through the straw

I’m more interested in humans. Is the mouth and anus two holes or one?

Poop. Beans. Here come the holes.

Well, depends what you call a hole. Does a glass have a hole? Does a bottle have a hole?

If you said no to both, you mean a topological hole and a straw has one.

If you said yes to one or both of them, you mean a tight opening in which someting can be inserted (yes yes, innuendo). How tight an opening must be to be a hole is arbitrary and subjective, it depends on the person. In this case a straw has two holes.

0. A straw is a continuous surface without any holes.

How far are you zooming in? I'd say there are basically infinite holes if you look at it at an atomic scale

One