How to guess the mystery number in guessing games

So, a friend just challenged you to think of a number between 1 and 1000, huh? Well, here's a simple way to guess the number without guessing random numbers.

Thanks to chooseausername for giving me the game

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Step 1: Half of what?

Ok, so your number is big. Like, big as 1000. Well, you don't just guess a random number. You say the number that's half of 1000. Well, how do you figure that out? You shrink the number down, of course! Take the numbers after the second digit down, leaving you with 10. Whats half of 10? 5, of course! After that, add the zeros you took off the 10 to the 5, making it 500.

tech-king says: Jun 30, 2008. 9:18 AM

i won! beat this: I'm thinking about a number between 0 and 1000. Try to guess it ! You said : 500? My number is lower ! You said : 243? Congratulations ! You won ! You found my secret number in 1 tries. Your score is : 1000 (Press Reset to start a new game.)

coolz (author) in reply to tech-kingJun 30, 2008. 10:42 AM

prove it! post a picture

tech-king in reply to coolzJun 30, 2008. 1:35 PM

will do.

coolz (author) in reply to tech-kingJun 30, 2008. 2:02 PM

ok. but someone beat that already. you cant beat him because he got the maximum score already

tech-king in reply to coolzJun 30, 2008. 2:39 PM

what if i hack?

coolz (author) in reply to tech-kingJun 30, 2008. 4:09 PM

1. that will get you disqualified 2. hacking wont help

zimmemic25 in reply to coolzOct 26, 2008. 1:41 AM

it helps! type this into address bar: javascript:alert(random_number); works in firefox and konqueror.

zimmemic25 in reply to zimmemic25Oct 26, 2008. 1:44 AM

I'm thinking about a number between 0 and 1000. Try to guess it ! ---> javascript:alert(random_number); <--- ---> new window opens: 656 <--- You said : 656? Congratulations ! You won ! You found my secret number in 0 tries. Your score is : Infinity (Press Reset to start a new game.)

tech-king says: Jun 29, 2008. 11:38 AM

game didnt work! it wouldnt display fractions, decimals or exponents. I'm thinking about a number between 0 and 1000. Try to guess it ! You said : NaN? You said : NaN? You said : NaN? You said : NaN? You said : NaN? You said : NaN? You said : NaN? You said : NaN? You said : NaN? You said : NaN? You said : NaN? You said : NaN? You said : NaN? You said : NaN? You said : NaN?

coolz (author) in reply to tech-kingJun 29, 2008. 11:40 AM

its not supposed to display those things

tech-king in reply to coolzJun 30, 2008. 9:09 AM

you mean it wont do fractions, exponents, roots, algebra or basic expressions? lowzy game.

coolz (author) in reply to tech-kingJun 30, 2008. 10:43 AM

no, its a game, not a homework machine

tech-king in reply to coolzJun 30, 2008. 2:41 PM

its not a smart program.

coolz (author) in reply to tech-kingJun 30, 2008. 4:08 PM

its made with html

zimmemic25 in reply to coolzOct 26, 2008. 1:40 AM

i know a neuronal net coded in html!

tech-king in reply to coolzJun 30, 2008. 7:04 PM

thus its a dumb program. it should freeze up at math.

coolz (author) in reply to tech-kingJun 30, 2008. 7:53 PM

its a game

tech-king in reply to coolzJul 1, 2008. 4:02 AM

and a dumb one at that

coolz (author) in reply to tech-kingJul 1, 2008. 10:54 AM

i didnt even make the game! if you're gonna complain, complain to chooseausername

zimmemic25 says: Oct 26, 2008. 1:38 AM

i needed 10 tries. the ****ing number was 559!!! how should someone guess it??? LOG: I'm thinking about a number between 0 and 1000. Try to guess it ! You said : 500? My number is greater ! You said : 750? My number is lower ! You said : 700? My number is lower ! You said : 600? My number is lower ! You said : 550? My number is greater ! You said : 560? My number is lower ! You said : 555? My number is greater ! You said : 556? My number is greater ! You said : 557? My number is greater ! You said : 558? My number is greater ! You said : 559? Congratulations ! You won ! You found my secret number in 10 tries. Your score is : 100

n8man says: Jul 14, 2008. 4:20 PM

Coolz really left!

mrmucox says: Jun 30, 2008. 1:15 PM

I win!

coolz (author) in reply to mrmucoxJun 30, 2008. 1:29 PM

NEW RECORD HOLDER!

congrats! you have the record forever because that was the maximum possible score!

n8man in reply to coolzJul 1, 2008. 6:54 PM

Looks like he hacked look at the one of the person who hacked.

mrmucox in reply to n8manJul 2, 2008. 5:39 AM

Ummm... no. You'll notice it's 500, my first guess. Anyone's first guess.

n8man in reply to mrmucoxJul 2, 2008. 8:34 AM

I just said that because I lost. No hard feelings.

Keith-Kid says: Jun 28, 2008. 5:05 PM

Haha!

coolz (author) in reply to Keith-KidJun 28, 2008. 5:27 PM

(removed by author or community request)

Keith-Kid in reply to coolzJun 28, 2008. 5:30 PM

Huh???

coolz (author) in reply to Keith-KidJun 28, 2008. 5:31 PM

can you beat my record?

n8man in reply to coolzJun 29, 2008. 6:47 PM

I tied it.

coolz (author) in reply to n8manJun 29, 2008. 6:52 PM

yes, but i have it because i was first

n8man in reply to coolzJun 29, 2008. 8:20 PM

I did mine at 3:43 P.M. PST. When did you do yours?

coolz (author) in reply to n8manJun 30, 2008. 12:27 PM

I set the record on the day i made this instructable! i beat you by 2 days!

n8man in reply to coolzJul 1, 2008. 5:30 PM

Ok you win. I agree with you on Skate

coolz (author) in reply to n8manJul 1, 2008. 6:44 PM

nope. this guy called mrmucox got the record...

n8man says: Jun 29, 2008. 6:47 PM

What is your highest score, mine is 200. (on my second try) You also have it wrong at the third step. You divide the difference of the higher and lower number and add/ subtract it to the last number you guessed and continue doing that until you get the number choosing either the higher or lower when the difference is odd. Good instructable though, it displays the best way to crack this puzzle.

gamer says: Jun 29, 2008. 11:47 AM

Where is the link to the game??! Very nice technique, but if would be nice to have a link to the game. Thanks. -gamer

coolz (author) in reply to gamerJun 29, 2008. 1:04 PM

step 4 has the link

gamer in reply to coolzJun 29, 2008. 3:28 PM

Sorry, I missed it.