A Maths Puzzle: Find the nine digit number

[BeastOfTraal]

the 5th digit has to be 5 even digits have to be even odd digits are odd. the first two digits have 4 possible choices the next 2 digits have 3 possible choices you know the 5th digit so one choice

the next 2 digits have 2 possible choices and the last two digits only have one choice left so

4 * 4 * 3 * 3 *1 * 2 * 2 *1 * 1 = 576 viable numbers to try

[PoketoMtg]

381654729 while watching another video by you. First things first the odds go in odds, even go in evens. You can assume is 5 and 7 go into the 5th and 7th spots respectively (multiples of 5 end with 5, and doubleing rule when dividing by 7). Next you find that 2 and 6 fill the 4th and 8ths spots as odd(2/6) are the only ways to make multiples of 4. Putting 8 in the second spot you need a 1 in the 1st or 3rd, to make a multiple of 3 and the last spot is other (4 cannot go cause 1+4=2mod3).

[PoketoMtg]

@PoketoMtg I'ld say it took me 10 minutes as I know most of the rules of multiplication

[AudioJustG]

I couldn't come up with a way to solve it myself. So I wrote a program with Delphi to check every single number manually. Sorry for cheating, I'm bad at math, but I wanted to know the answer without looking at comments or anything :(

[jofer123062]

381654729 in less than 30 mins. the trick is simply to know your divisibility rules for each number.

[PukeOfThePukes]

THERE IS A CURSE!!! GIVE ME A CALCULATOR!!! NOWWWWWW

[kdmq]

Thumbs up if you think that all the thumbs ups on the comment of the correct solution places it at the top of the page and ruins it for everyone.

Also thumbs up to place this comment at the top of the page so that this puzzle isn't ruined for everyone!

[HaslamCorp]

381654729. Ok, the 5 was easy, and I zeroed in on the 654 in the middle after just a few trials. After that I made up a grid for the first three numbers and started trying them. It worked on the 7th try out of 16. Glad it worked, I didn't want to abandon the 654 in the middle.

[alancheira]

@HaslamCorp @HaslamCorp I got the same result. I narrowrd down using the 5 first, also, and then the divisibility per 2, then per 8, and went backwards. Luckily the 2 try was divisible by seven at the end, that was my fear. :)

[RandomNinjaOfEvil]

At least you found a use for them, huh!

[elizze6]

I got up to 723654 with no errors but then I got stuck

[TheAnonymousParadox]

I got 381654729; the only solution.

[GammahooX]

I cheated and wrote a Computer-Program to calculate it :D

Using a recursive function the progam needs a fraction of a second to calculate the number. I got:

381654729

[001GRad]

#lol

[001GRad]

#lol

[falafel1995]

Any number works, it is just not whole.

[bambam111992]

...then its not divisible by definition.

[PCGamerPortal]

@falafel1995 In R, not in Z.

[TyYann]

I did that with my middle school students last year.

[jonoiskool]

YEAH!!! 381654729

zomg only took me 2 hours n i didn't cheat TYVM! time to listen to some music!

[TapeWalletsCO]

@jonoiskool You shouldn't have spoiled it for others.

[jonoiskool]

@TapeWalletsCO have a cry noone cares. If you didn't want it spoiled you shouldn't have read the comments. But of course that's what a SMART person would do.

[hyldago]

the worst marked cards are the ones that are marked incorrectly =P

[gC222SA]

humm my math teacher gave us ext book that had a page with like ''all number divisible by 7 add up and divide by bla bla ba,i could look it up,but that MGITH make it not a puzzle...

[Moorich]

Late, but it's 381654729 and i solved it in a bit less than 3 hours without a calculator woohoo! I'm probably gonna die from all the mental calculation now yay!

[KronicDemon442]

every os has a calculator on it.

[scotland7yard]

cant wait for the solution!

No. 7 is giving me a terrible headache

[singingbanana]

Sounds like you're doing it right then, I found number 7 to be the pain.

[Elidragonguy]

Hmm... good challenge, i have a feeling i'll be working on this for a while...

Edit: saw answer in comments, sadness follows.

=[

[rotnakleugim]

381654729

[Strijdparel]

Could you give a hint, it is to difficult, I dont know where to start... :S

[dungeonmunky]

Because I'm a computers guy and not a maths guy, I wrote a computer program to solve it, which gave me the answer 381654729 (which is the only solution).

And because I'm lazy, instead of making a new program to do this, I just modified the code I used to find all solutions of the n Queens on an nXn chessboard.

[gC222SA]

wow smart,theres rules to dviding,like for 9 the first 3 digits have t divide by 3,do your supose to re arange to fit all the rules,i wish you were sopposed to send in results,lol reading the comments takes all the fun out of the puzzel XD,i just checked,yep it works

[jimbob4evatoday]

the solution is: 381654729.

[qzervi]

lol i got it 1st in the previous vid XD

[singingbanana]

I wasn't happy with the version I uploaded 12 hours ago. The old version is still there for now.

[agurkas321]

...and why is that so..?

[singingbanana]

There is only one sentence different, but it was important.. Now the audio is worse in this one!

[agurkas321]

its fine! :D

[TheBreezCast]

It was the using each number once part right?