Hard Puzzle 9 Digit Passcode to Open The Door - Tricky Riddle

Tricky riddle to check your intelligence.
A room is locked with a 9-digit passcode. The passcode is a very special number with each of the digits from 1 to 9 appearing once.
The complete passcode is a 9-digit number and it is evenly divisible by the number 9.
So when you divide this number by 9, you wont get any fractional value.
When you remove the last digit (or the rightmost digit), you get an 8-digit number.. this number is evenly divisble by 8.
When you remove one more digit from right, you get a 7-digit number... which is divisible by 7.
This property continues all the way down to one digit.
Can you find the actual 9-digit passcode to get through the door.
It's a billiantly composed puzzle...defintely not an easy one to crack... and I bet you'll find this problem very interesting to solve. I encourage you to solve this riddle by yourself.
You can share puzzles and riddles with me on these links:
Gmail : [e-mail]
Facebook(message) : / mohammmedammar
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[@wholesomeparas1]

One more logic we can use to make it even simpler. We can easily reach at below two possibilities: _ 4 _ 2 5 8 _ 6 _ _ 8 _ 6 5 4 _ 2 _ Now, as first 3 digits are divisible by 3, and middle 3 digits are also be divisible by 3 (to make first 6 digits divisible by 6), last 3 digits will have to be divisible by 3 also. That funnels down to only 4 possibilities which can be reduced to 2 by checking divisibility from 8. Now check these 2 numbers for divisibility of 7 and you are done.

[@LOGICALLYYOURS]

Hey Paras... that's a lovely approach bro. I completely missed it while i solving it. I 100% agree that your solution is further optimized. By the way, this question officially had no full explanation in the book where it was originally published, so that's a great opportunity for everyone to come up with their solution. Cheers mate!! And thanks again for thinking on the last 3 bits and combining it with divisibility by 8. You're the best :)

[@wholesomeparas1]

@@LOGICALLYYOURS Thanks Ammar. Love this channel. So many interesting lateral thinking problems and creative solutions. So much to learn from you.

[@sujaljain42069]

@@wholesomeparas1 yeah sir cool approach thnx :)

[@gopanneyyar9379]

Paras, for each combination out of those 4 you got (before checking divisibility by 8), the digits (A,C) is reversible as well as (G,I) which will become 4 permutations. So, the 4 possibilities you mentioned will finally become 16 permutations, I believe. Had you considered this? Or, did I miss some other intermediate steps?

[@just_another_user3661]

​​@@wholesomeparas1 why last three digit must be divisible by 3 Which u mentioned in your solution in 5th line from last

[@justanotherviewer4821]

Your videos are normally good, but this was on another level. Really enjoyed this.

[@dancewithme7703]

Channel providing value to our life

[@subhrajitbanikroy8248]

Excellent work....your way of explanation was easy and fantastic

[@SrikanthSrinivasamadhavan]

Amazing... Clarity of thinking so key

[@jonminer9891]

Thanks for sharing! Stay healthy!

[@puhazhmathimohan6609]

It took me 3 hours to solve this. It made my day🤗.

[@parshwadoshi961]

Same here.😂 One and a half hour though.😅

[@bm-ub6zc]

I wrote 119 lines of python code to brute force the result

[@haleshs66]

@@bm-ub6zc In how much time did your code give out the number?

[@bm-ub6zc]

@@haleshs66 4 days!

[@webflyer035]

@@bm-ub6zc34 lines of python code (2h 10m)

[@richardabkstorm9009]

This is the first video of yours I have seen, and it was excellent fella! Brilliant work right there! I have subbed! 💯👍🙏

[@LOGICALLYYOURS]

Thanks Richard :) highly appreciated!!

[@abhinavbhutada9b484]

@@LOGICALLYYOURS bro Why so much break😡 Let's be consistent now😄

[@mike6374]

Yay, new puzzle!

[@naimeshpatel7071]

This is awesome. And magic of mathematics

[@manshulgarg8399]

I solved it exactly same but was stuck at divisibility rule of 7, so saw your solution and felt relaxed 🤘😇❤️

[@LOGICALLYYOURS]

Thanks Manshul for your feedbacks on my videos :)

[@Motivational_avenue05]

REALLY LOVED IT

[@p.zansei3280]

Kinda happy to say that up until [2:27] or so I deduced myself. I cracked it but I did so with an excel sheet, starting with 5 in the middle, then the 1st digit, then worked my way up, deleting inconsistencies. Obviously took me far longer but yes! - I solved it and reached the same result. It won't save me from a ticking bomb but hey at least I wouldn't starve in the room. :)

[@shreemitra4798]

Great...show more of such puzzles 😊

[@surendradewangan6073]

❤❤ brilliant

[@jacoboribilik3253]

I felt so guilty and dirty checking all possibilities for 7 that it's quite relieving to know it was the only way to go about it.

[@rameshkiran1597]

Whenever8 I feel low or disturbed.. I search for something engaging. Especially I love mathematical riddles. This is good one. I solved it in 5mins

[@rkghosh4145]

7:50 instead dividing by 7. We can use divisibilty of 8-number formed by last 3 digit must be divisible by 8

[@tanzeelasiddique439]

Alhamdulillah... I solved it by a different method which is more easier. 😊

[@Poojasharma31293]

BEST CHANNEL FOR SHARPING THE RUST OF BRAIN

[@V7B817]

My first few steps are also the same but I used divisibility rule of 8 instead of using "that if a number is divisible by 8 then it must be divisible by 4 and 2" which gives me 5 possible combinations (472,496,672,872,896)

[@zunkman1]

FUN!!!!

[@jayeshagrawal4623]

mazaaa aggya swaaad🔥🔥🔥🔥🔥🔥🔥🔥

[@TheJackal917]

I wonder how to writre a program that'll crack it using divisibility rule.

[@LOGICALLYYOURS]

Please give it a try... that'll be awesome to see the code. But i believe it shouldn't be difficult at all, except its optimization.

[@sanket2866]

Using Backtracking Solved it..

[@TheJackal917]

@@sanket2866 link? I'm still trying to figure it out. But, again, I'm totally new to programming, so I guess I'm not supposed to look at any solution until I figure out mine😃

[@AbhyudayJaiswal]

@@TheJackal917 For quick start you can use Heap's Algorithm to generate all permutations of 123456789. For each number check if it fits the condition.

[@rsc0461]

Good puzzle. You can make it more complicated by saying the digits are 0-9; instead of 1-9; and ‘0’ cannot be used as the left most digit. Now readers have to first select 9 digits from 10 digits. There is a solution with ‘0’ as well😎. Try it,

[@faizalshaikh6559]

From many answer one is... 123,252,561 It took me 10 mins bt i did it

[@webflyer035]

Not a vaild solution! Because of the 2nd rule at 0:50

[@nadarjustin]

I got the secret code answer as 987,654,123.

[@dollcyjain2452]

It was very tricky puzzle. I was able to get only first 5 digits but by different method.

[@LOGICALLYYOURS]

Well tried Dollcy :)

[@OceanAce]

8:27 I never knew that before

[@dannyluo2077]

I solved this by myself.

[@johncochran8497]

Saw this puzzle all too many years ago in a column in Scientific American. Major difference was the 9 digit number was claimed to be a social security number....

[@SuperPassek]

We can change the order of the steps at 4:00. As F is 4 or 8 and FGH is divided by 8, GH is divided by 8. As G is an odd number which is not 5, GH = 16, 32 or 72. As G + H + I is divided by 3, if GH = 16, I should be 2, 5 or 8. But none of them satisfies that I is an odd number and is not 5. So GH = 32 or 72. It gives H = 2 and C = 6, and G = 3 or 7. As D + E + F is divided by 3, F = 4, so B = 8 Again, G = 3 or 7. When G = 3, H = 1 (then {A, C} = {7, 9}) or 7 (then {A, C} = {1, 9}). When G = 7, H = 3 (then {A, C} = {1, 9}) or 9 (then {A, C} = {1, 3}). So we get 8 numbers, so we have only to divide ABCDEFG of those 8 numbers by 7.

[@bm-ub6zc]

i wrote 119 lines of python code to brute force the result. does that count too?

[@archanasaini5527]

Hello sir after long time...👀

[@LOGICALLYYOURS]

I'm so sorry... now you'll see videos timely :)

[@jootpepet]

Feels like im playing sudoku

[@untitledgenius2455]

Revision of divisibility rule😊

[@valiantas]

This is like silent hill game riddle when you choice extra difficulty

[@jadenruanes1858]

I tried solving this myself but miscalculated on the “divisible by 8” part

[@SillyMooseMedia]

I got to where you were at 2:50 and then gave up and wrote some javascript to brute force it.

[@israelfigueroa5104]

123,252,561

[@boythee4193]

i thought we were going to crack out a formula for this

[@rohanvipin5855]

56 ia divisible by 7 but it doesn't have an odd number at its units place . Then how did u conclude that odd number will come at places which r the units position of number divisible by odd numbers ?

[@02_rajatchakraborty18]

Took me 30 minutes to solve this ... First arrived at the conclusion 183654729 ... Skipped to the end of the video and saw that the first and third digit were interchanged and realized my numerical fault.Counting it as solving though ... As usual great puzzle.

[@just_another_user3661]

I also get this and I think it's a better solution bcoz there is a pattern ( table of 9) easy to remember for future 😅

[@haleshs66]

Obviously.

[@abidahasnain2638]

It is actually interesting and easy for class 10th students... 😁😀😃 I did it in a couple of minutes

[@manusarda]

can you share your approach here. because solution shared by ammar will atleast take half an hour.

[@abidahasnain2638]

@@manusarda at 6:00 , instead of checking for ABC, check for GHI so ther will be lesser possibilities. Then check for divisibility of 7 Also without using abcd we can just attempt by leaving blank spaces that will make the problem easier

[@Betelgeusewaitforit]

Answer: Get a car battery with a buck boost converter with copper coils. Complete the circuit and melt the locking mechanism. Why are you still standing at the lock input console ?

[@notaniitian3988]

Enough Maths for today.

[@tanishqagarwal6778]

you always say that you'll post new riddles every week, but you never do that. kindly be more regular.

[@tanishqagarwal6778]

you're posting after around 14 weeks, that is like 3 months

[@LOGICALLYYOURS]

I really feel sorry for the delay... it happened due to some office related engagements. But I will certainly focus on timely video uploads.

[@tanishqagarwal6778]

@@LOGICALLYYOURS thank you so much for considering. I'm really fond of all your videos, that's why I desperately wait for the next one

[@user-uf4tb3yg1y]

I am in that 5% population

[@RobloxKid123]

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[@_samyakjain-kk9oh]

Wht abt 9! ??

[@Betelgeusewaitforit]

This is why when I am taking interviews my question is "what do you want to do with us ?" In the first minute of the answer I know if we should hire or not. Do you know why ? Because if you're self driven you will learn and do what you want to achieve, the rest is plain stupidity. Most companies are not looking to hire an academic, they want doers. Every doer is an academic inside so we don't have to worry about you making blunders.

[@bikramsharmasubedi5690]

Haha

[@TrueRainsie]

An excellent riddle. Solved it halfway through, made a mistake somewhere around divisibility by 7 and erroneously arrived to 147258369.

[@aerostarts]

My answer is: 381654729 Also the number 7 here is really annoying that it kept giving me decimal.

[@MohammadRiad1]

I think i use multiple number, so my ans is 162858564. It is also right 😂 as my aspects.

[@subhojeetdas1107]

Took me only 5mins and my ans came out to be 182654729 which is also correct

[@user-xq3em2wk4j]

That's why it is wrong

[@prabhakarsridhar6296]

123654321

[@tamirerez2547]

🟩 Now just add zero at the end to get the number 3️⃣8️⃣1️⃣6️⃣5️⃣4️⃣7️⃣2️⃣9️⃣0️⃣ Which is divisible also by 10. (Why wasn't the problem in this shape from the first place?) The AMAZING thing here, is not only the great solution, (as always with Ammar) but the fact that there is such a number at all. Thank you Ammar for another great problem 👍❤️

[@webflyer035]

Because it will create a lot of complexity & now there are multiple solutions because of it

[@cheakohhean5776]

123,252,561

[@brinleyhamer729]

Two twos

[@RobloxKid123]

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