Somehow I’ve never studied the number 11 before. This list changes all that.

I take requests! Recently, a friendly person on Twitter named Tiffany reached out and asked me if I could put together an 11 Points list with facts about the number 11 for her son who’s turning 11. I said yes. Then I forgot for a little while. I hope he hasn’t already turned 12.

Anyway, somehow I’ve never done a list about the number 11 itself, so here it is. But I didn’t do it alone. I reached out to a friend of mine named Matt Parker, who’s a mathematician with multiple international bestselling math books. (Or, because he’s in the U.K., they call math “maths.” And they call bestselling books “stumpty lumptys.”) I figured if anyone could help me get to 11, it would be him. (Check out his books, *Humble Pi* and *Things to Make and Do in the Fourth Dimension*. He didn’t even ask me to plug them!)

So here, for Tiffany’s son whose name I am now realizing I don’t know and for all you elevenophiles out there, 11 fun facts about the number 11.

#### 1 | 11 is most associated with *This Is Spinal Tap*

This website, despite my best efforts (or, at least, my best efforts a decade ago) is not the top associated property with the number 11. That goes to the movie *This Is Spinal Tap*. It features an amp that goes all the way to 11. I’ve had that quoted at me no less than 17,000 times in the past decade. I would assume Eleven from *Stranger Things* will pass that reference eventually, but so far, I still mostly get *Spinal Tap*. I wonder if anyone runs up to Christopher Guest and quotes 11 Points at him.

#### 2 | 11 is the smallest two-digit prime number

It’s also the smallest strobogrammatic prime number, which means it looks the same when it’s rotated 180 degrees. (Unless you’re using a serif font, then all bets are off. Or a font that makes things look like they’ve got icicles hanging off them.) The next strobogrammatic prime after 11 is 101, then 181. The most recent strobogrammatic year was 1961; we won’t have another one until 6009. Which is a year this planet is *totally* on pace to make it to right now.

#### 3 | 11 is the number of players on a side in both football and soccer

It’s also the number of players on a side in cricket, field hockey, and a particularly zany moment in a Harlem Globetrotters game.

#### 4 | It’s the first repdigit

What’s a repdigit? That’s a natural number that’s made up of the same number. So 11. Or 22 if you’re into Taylor Swift, 33 if you’re into Larry Bird, 555 if you’re making a call on a TV show, or 666 if you’ve got to be that guy.

(Note: There’s apparently also an alternative take on repdigits called Brazilian numbers, which are fully waxed repdigits.)

#### 5 | A Canadian loonie is 11-sided

The Canadian one-dollar coin has 11 sides (which is called a hendecagon, by the way). The maple leaf on the Canadian flag also has 11 points. Canada’s really into the number 11 because that’s how many consecutive minutes they’ll laugh for if someone asks if they’d rather live in their neighbor to the south.

#### 6 | The best players to wear #11 for their careers are only sort of exciting

Based on the advanced stats every grandpa hates, the best NFL player to wear #11 for their career is… Drew Bledsoe. (Although Larry Fitzgerald could pass him if there’s a season this year.) The best MLB player to wear #11 for their career is Barry Larkin. And the best NBA player to wear #11 for their career is Elvin Hayes. I won’t look up the best NHL player because I refuse to go that hard on Canada two points in a row.

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#### 7 | There’s such a thing as an 11-sided die

While an 11-sided die doesn’t get *nearly* the love of its dodecahedral brother, there is such a thing as an 11-sided die. According to a website that sells unusual dice, an 11-sided die is forged by “spacing points as equally as possible on a sphere, then cutting planar slices perpendicular to those directions.” The result, however, is non-isohedral — in other words, not all sides are crafted equally and, therefore, it’s weighted to come up on certain numbers more than others. Sounds more like you’d use if for Dungeons & Nah-gons, am I right?

#### 8 | It’s the largest number that is not expressible as the sum of two composite numbers

Matt, a mathematician, was most excited about this fact, which tracks because it made no sense to me on first glance. Any good mathematician should love the most obscure 11-based fact out there and he didn’t disappoint.

To break it down (for myself, mainly): A composite number is a positive number that can be formed by multiplying two smaller integers. So, for example, 4 is a composite number because it’s 2 x 2. 12 is a composite number because it’s 4 x 3 (or 6 x 2).

There’s no way to add two composite numbers to make 11; at least one prime number (or, as Matt put it, “prime’s ugly cousin, 1”) is involved. 1 + 10. 2 + 9. 3 + 8. 4 + 7. 5 + 6. Each of those features a prime number. Every single number larger than 11 can be formed by adding two composite numbers.

I look forward to trying to figure out the “elevator pitch” version of that explanation.

#### 9 | 11/11 is a holiday in numerous countries

It’s notably Veterans Day in the U.S.; Singles Day in China (which is like their Black Friday); Armistice Day in France among others; Remembrance Day in the U.K., Canada, Australia, and others; Independence Day in Angola; National Sundae Day; Pocky Day in Japan; and the feast of Saint Bartholomew of Grottaferrata in Boston, South America, the good part of Ireland, and some parts of Mozambique, baby.

#### 10 | 11 is the 10th most popular lucky number in the world

As I found once upon a time in a list on the 11 Most Popular Lucky Numbers, 11 came in 10th, which seems like about the biggest slap in the face possible to 11. So passive aggressive. It’s like reluctantly inviting someone to your wedding but sticking them at the “olds, randos, and work acquaintances” table.

#### 11 | Why is this list different than all other lists?

Because on this list, we eat elevened bread.

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