I know this is going to sound crazy, but it actually works. There is so much math all around us, built into the very fabric of the universe, filling every corner of our technological society — but most people just ignore it or don’t even realize that it’s there.
Here’s the idea — with a little practice and “tuning in” to the numbers all around us, you can learn to guess numbers that other people are thinking of — not that you will be right all the time, but you will be able to do much better than you would just by random guessing. The fact is that when you ask someone to “choose a number between one and ten”, their choice is not “random” but is actually influenced in subtle ways by the numbers all around them — their age, phone numbers they know, numbers they have just recently been thinking of, or numbers that are printed on things that they can see. (For example, stop right now and take a look around you, wherever you are — how many numbers can you see? Probably hundreds.) By being aware of this you can learn to guess what numbers people have “randomly” chosen.
The first step is to spend some time becoming aware of the numbers around you — “tuning in”, so to speak. Pay attention to numbers you see around you, and numbers that you hear people say. Although it doesn’t help directly with guessing numbers people are thinking of, I’ve found that doing things like reading the digits of pi out loud can help just by getting my brain in a more “number-mindful” state.
After that, it just takes practice. Ask your family and friends to choose a number (start with a number from 1-10, but with more practice you might be able to do 1-100). Then try to guess what number they’re thinking of. But don’t just guess randomly: try to be aware of the surrounding “number environment” — numbers that have been spoken recently, numbers printed on things nearby, and so on. (If you’re really clever you can try to do things like work a certain number into conversation several times before having the other person choose a number, to try to subliminally influence their choice; but be careful not to be too obvious.) Above all, try to sense what number it “feels” like they are thinking of. I know that sounds silly; of course, mind reading isn’t actually possible, but what I mean is that if you are “tuned in” to the number environment, your subconscious might suggest a number without your conscious mind really knowing why — which can feel a lot like mind-reading even if there are actually more complex and realistic things going on.
Of course, don’t be discouraged if you don’t do very well at first! It will take some practice before you start to get better at it. And even the best number-guessers can’t guess correctly all the time. If you can guess correctly one out of every five times, you’re doing extremely well! (Remember, by pure chance you would only expect to guess correctly one out of every ten times, if the other person chooses a number from 1 to 10.)
Happy guessing! Feel free to comment and let me know if it works or doesn’t work, interesting experiences you have trying this technique, or anything else.
The Math Less Traveled 
this actually worked! i tried it out on my dad, and i before i guessed what number he was thinking of, (1-10), i just kept saying 4 word sentences, and when i guessed the number after a while (i guessed 4), i was right!
haha! That’s awesome. In general I meant it kind of as a joke, BUT there are definitely bits of truth in there. Did your dad realize how you did it, or was he impressed?
i said 8 a few times and and told my siter to guess a number and i got it right 3 times it was 7 then 9 then 8 it revolved around the number i said.
Hey–
There’s also a certain predisposition to guess numbers that are… well, less round. Asked to guess a number between 1 and 10, most people I know would cluster guesses at seven and four. (If I remember correctly, it’s something I observed a lot in high school.) There are a few people who will guess one of the endpoints of the number range because they just heard it, and a few people who will guess five because it’s… well, five. But people tend to shy away from those three because they’re sort of too obvious, or because they’re terminal, or just because people are silly that way. Four and Seven are both sort of conventional lucky numbers.
Oh, and people sometimes double-dip into non-obviousness–instead of four and seven, they’ll go to three, two, or… maybe nine? Usually because they know the common numbers are four and seven, and these feel less obvious.
Note, of course, that this is all emprical and anecdotal, generalizations that seemed to hold true for most of the occasions where it comes up. Still, it would be interesting to see a statistical breakdown. (Or, for that matter, to see if there was any variation according to economic status, geographic region, education of parents, etc…) Mmm…
(But not interesting enough for me to do a study. =))