A short history
The book containing a million random digits
Some books have a twist ending. This one has a million random digits. Published in 1955, it sounds like a joke gift—but there was a very good reason to make it.
Skip to the experimentImagine asking a librarian for a book full of numbers with no pattern to follow. No story, no puzzle to solve. Just a great many digits, ready whenever you need one.
In 1955, RAND published exactly that: A Million Random Digits with 100,000 Normal Deviates. Researchers needed large supplies of numbers for experiments that used chance to work through a problem. A ready-made table was useful equipment.
Making it wasn’t simply a matter of typing whatever came to mind. An electronic roulette device produced the raw digits. Tests found small biases, so the numbers were transformed before the finished table was published. RAND tells the story in its introduction.
But how do you actually use a page like that? Let’s give it a small job.
to start.A table you could keep on a shelf.
The digits here are our own.
Imagine a list of 100 names. Read a pair from the page and add one: 00 picks name 1, 42 picks name 43, and 99 picks name 100. Have a go.
Who does the page choose?
Start with 100 names on an imaginary list. The page will help you pick one.
Start at the first outlined pair. Read across, then down.
We’ve made this small table just for you. It isn’t taken from the book, and a pair can come up more than once.
A page that makes decisions.
There’s something pleasingly simple about it. You don’t have to choose a number you like, close your eyes or argue over who gets to pick. You decide how to read the table, then follow along.
In our version, you start at the top left and read across each row. Every pair from 00 to 99 has one matching place on your list. That’s why we add one: the page starts at 00, while your names start at 1.
The page can repeat itself, just as separate coin flips can both land heads. If you’re choosing different people, you’d skip any name already chosen. Our little demo allows repeats so you can see the table at work.
Now take forty names off the list.
Switch the demo to 60 entries. A pair of 42 still works: choose name 43. But 87 would point to name 88, and your list doesn’t go that far. So you skip it and read on.
It may feel wasteful, but skipping those pairs keeps things even. The sixty names each get one pair that can choose them: 00 through 59.
What if you simply wrapped the extra pairs back to the start? Then 00 and 60 could both pick name 1, while name 41 would only have 40. The names near the top would quietly get extra chances. Skipping avoids that little unfairness.
Same small question, a very different desk.
You probably won’t keep a huge number table beside your phone. But the old exercise leaves you with a good question: does every name—or number—have the same chance?
That question matters whether you’re following a line on paper or tapping a screen. A method can look wonderfully simple and still need a little care behind the scenes.
Try the table once more with just ten entries. You’ll usually do more skipping. The page is being fussy for a reason: everyone on your short list still deserves the same chance.
About this table and the original book
The demo makes fresh digits in your browser using Web Crypto; it doesn’t copy RAND’s table. The original book’s tables were prepared mainly for punched-card machines, and RAND reissued the book in 2001. You can read the introduction and download the tables on RAND’s publication page.
Or let the screen do the reading.
Choose your range. We’ll take care of the pick.
Pick a random number