Would you want to make over 6 billion cups of tea for them?

It's always fun, when you're in a particularly odd conversation (given my friends, most of my conversations are odd) to drop in interesting and unlikely facts that you've heard recently. One of my enduring favourites is that if you squashed them a bit, you could fit every single person in the world onto the Isle of Man.

The reaction I get to this fact is always good (that's why I keep mentioning it), and if you're anything like most of my friends your reaction just now will have been "Surely that's not true." Well, it's easier to verify than you might think. Gather round, children, because it's time for a session of Uncle Phil Makes Arithmetic Fun!*

We'll start with the population of the world. At the time of writing, the US Census Bureau estimates that there are 6,590,618,635 people around. Obviously that's not going to be perfectly accurate, but it's good enough for our purposes. Now we have to allocate land so that each one of these people can stand up - a square of about 40cm x 40cm should be OK. There will be plenty of obese people who need more space than that, but on the other hand there will also be a lot of babies and toddlers who need significantly less, or who can be carried by their mothers. The CIA Factbook reckons that 27% of the world's population are under the age of 14 anyway, so if anything 40cm is generous.

Our 40cm square takes up 0.16 m², which, when multiplied by the Earth's population, gives us a total land area of 1,054,498,982 m², or 1,054.5 km². Now, by this measure, we can't get everyone on the Isle of Man, not by a long way - that has a land area of 572 km² (CIA Factbook again). We can comfortably get everyone on the Isle of Skye (1,656 km²), though.

Let's not give up on the Isle of Man just yet. Our estimate of 0.16 m² per person was assuming that everyone is standing next to each other - fairly tightly packed, yes, but definitely not as close together as they could be. The classic measure of people packed closely together is the good old "students in a phonebox" trick, and the current record for the number of adults in such a phone box is 12. (I'm not bothering with the records that included children - that would just be silly.) Red phone boxes are around 3' square, giving us a land area of around 0.0675 m² per person. If we pack the entire world that close, we're now looking at a mere 444,866,758 m², or 444.9 km².

So there we go. It is indeed (theoretically) possible to fit the entire population of the world onto the Isle of Man. This would raise the population density of the island to 11,522,060.55 people per km², about 487 times the density of the current record holder (Monaco, with 23,660). Of course, the practicalities of actually doing so would be prohibitive, and it would be a bit daft to even suggest it's possible, wouldn't it?

So if we were to try and put everyone on the island, it would have to be pretty flat, as we need all the available space. Because the Isle of Man currently has a population of 75,831, assuming 3 people to a household we'd need to demolish 25,277 homes, not to mention all of the shops, factories and other buildings. Now, if we wanted to make sure that we'd crammed them in tightly enough, we could always supply the requisite phone boxes, which, given that they weigh about 750kg each, would require us (at a rate of 12 people per box) to import 411,913,664.7 tonnes of material. Or, to put it another way, enough stuff to outweigh all of the steel produced by China in 2006.

While everyone's there, it would be rude not to give them something to eat. A ham sandwich would do, I reckon. Assuming that a slice of ham weighs 15g, this means that we're using 98,859,279.53 kg of the stuff in total, or approximately 870,000 pigs. That's about as many as were present in the whole of Colorado in 1998. After that we'd definitely need to have a game of something, too. I mean, would you want to have to come all that way and then just go home? Twister's always a good choice. There is the minor problem that a Twister board big enough to accommodate everyone (that is, 4 spots per person) would require 26,362,474,540 spots, and given that a normal mat only has 24 and takes up 2.45 m², we would need a mat that took up 2,688,972,403 m², or 2,689 km². Luxembourg would just about do (we could always use a bit of Belgium if need be).

This concludes our lesson for today, everyone. Thanks for being such good students. Hurry back for more improbable-sounding facts soon!

*Uncle Phil may or may not make arithmetic fun. Uncle Phil is not actually anyone's uncle. No discounts, exchanges or refunds. Do not attempt arithmetic unless you have been examined by a competent medical professional and declared safe to do so. Avoid operating heavy machinery within 5 hours of attempting arithmetic. If you are pregnant or lactating, seek medical advice before performing arithmetic.