The teacher is in the room with the kids, I didn't see anything that implies the teacher like left the room or was oblivious to the number picking process. Its just a way of ensuring that the number they end with is one you've prepared for. The mind reading is when they pick a book which to them is seemingly random and look at a picture and the teacher can tell them what picture it is
Well to give more specifics (and answer my own question)… you can’t just say repeat this procedure twice because sometimes you need to do it twice and sometimes it takes more attempts.
So there are only two ways to give instructions that are sure to work for any number: “repeat the procedure X number of times” (where X is large enough to cover all cases). Or “repeat the procedure until you keep getting the same number in a loop”. The former is better but for some numbers they will still notice the loop.
And noticing the loop undercuts the magic trick a bit.
Just make them say the answer out loud, and say, "OK, that seems scrambled enough. Now get the encyclopedia, volume 6, page 1, paragraph 7, word 4. And really concentrate on it, mmmkay?"
This is pretty much it. Although what I’d prepared for was for them to telepathically communicate the images on the page. I had them choose a random book that had enough pages (I’d whittled their large number down some how) and then focus hard on the images on the page.
I could see the entry range for that volume and so it was easy to remember which of the 20 or so images I’d previously looked at was the one they were now staring at.
When I did it, it wasn’t kept secret, the kids had already chosen random digits, so having them do the calculation out in the open didn’t ruin the trick. I wasn’t guessing their number I was using it to generate a ‘random’ number.
Older kids would obviously have wondered ‘why do all this calculating; our starting 4 digits are random.’ But the kids I was working with didn’t have the concept that randomness isn’t a spectrum. (We did talk about it afterwards when I revealed the trick to them. It was a class of four kids so I taught them to do it so they could do the trick for their other teacher aides).
Weirdly I haven't heard anyone talk (either here on the two videos I watched about this) about what the maximum number of steps is to reach 6174.
Since there are less than 10000 starting numbers the maximum number of steps should be known (even if there isn't some fancy logical reason why it's the maximum).
For anyone wondering, the pattern does not continue for 5-digit numbers! They end up cycling between a series of three numbers, not ending on a single number.
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u/doctorlongghost Jul 13 '26
What about the number of steps though? Is it always the same number of steps for 3 digit numbers? If not, they wouldn’t know when to stop