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Questions tagged [number-sequence]

A puzzle that asks for the pattern in a given number sequence.

49
votes
4answers
8k views

Interview Question or Pathbreaking puzzle

I thought this changes the way series of numbers are looked at 1 1 1 2 1 1 2 1 1 Write down the next three lines
25
votes
1answer
2k views

Four is Cosmic!

This is a little puzzle I heard a while back from one of my mathematically inclined friends- I get the sense that it's bounced around a little, so forgive me if you've heard it. There is a sort of ...
4
votes
0answers
215 views
+50

Number sequences: 000, X00… and 6X000X9, 700XX08

Q1: 000,X00,?,XX0 ,X00 Q2: 6X000X9,700XX08,00000015,?,00000015,?,00000015 These two questions actually come from the puzzles made by my friend. He gave me his puzzles recently but I couldn't figure ...
13
votes
1answer
462 views

Two honeycomb hints (yet another 'find the next number in the sequence')

Find the next number in the sequence $1,7,74,\dots$ First hint: Second hint: To clarify: the 'hints' are really clues. They are hidden, because any of the two alone could be enough to solve the ...
6
votes
8answers
50k views

Fill the holes? [closed]

You have to fill the boxes to make the equation true:   +   +   = 30 Using only 1, 3, 5, 7, 9, 11, 13, 15. You can also repeat the numbers. (eg: 1 + 1 + 1) Edit1: the boxes of the equation are ...
55
votes
1answer
3k views

Mysterious message from the NoSlaves™ Calculator Co

So my son is starting to show an interest in mathematics, and being the awesome dad that I am, I decided to buy him a basic calculator. Being the cheapskate that I am, I ordered the cheapest one I ...
4
votes
0answers
215 views

What are the alphabets in the question mark?

BDCBAF :: ADBFCC :: CEBCAG = PDL :: XRI :: ? This alphametic question actually comes from the puzzles made by my friend. He gave me his puzzles recently but I couldn't figure it out. Any clues? ...
1
vote
2answers
3k views

What is the next number? 24,54,90,120,168,210,240,288,360,440 [closed]

Question : What is the next number in the following sequence? (not finite) $$\large24,54,90,120,168,210,240,288,360,440,\dots$$ My Solution I'm trying a closed form solution I tried computing ...
-1
votes
3answers
960 views

Complete the number-sequence

2 → 6 3 → 12 4 → 20 5 → 30 6 → 42 9 → ? Can you find a correspondence between these numbers? It's not mine, so I don't take any credit. I've just seen it in Linkedin and wanted to share with ...
-2
votes
1answer
5k views

What is the next number and why? - 11,21,1112,… [duplicate]

Simple logic question, what is the next number and why? 11, 21, 1112, 3112, 211213, 312213, 212223, 114213, ?
22
votes
1answer
4k views

Very simple, yet unsolved, sequence of numbers

A simple sequence of numbers, which I encountered during intermediate school, in my math book. Any person that finished intermediate school possesses the necessary toolbox required to solve this ...
25
votes
2answers
18k views

What is this magic trick with 6 cards featuring numbers between 1 and 60?

I hope this is on topic. I have a set of kids' magic tricks but I have lost the instructions! I was hoping this might be a good place to get some help. Here is the first one. What is the trick and ...
10
votes
3answers
556 views

Two missing numbers

Two numbers go at the $?$s, what are they and why? $733,\space \space 716,\space \space 645,\space \space 565,\space \space 324,\space \space 276,\space \space 77,\space \space 75,\space \space 64,\...
-4
votes
10answers
881 views

SafeCracker #3 - We've Been Blocked [closed]

Our Last Safe To Conquer Ok, team, this one might give us a little trouble. Nothing we can't handle though... let's go... This safe model is "The NevaCrak 9000" - the most secure safe there is. ...
10
votes
2answers
2k views

Seeing the forest for the trees and all that jazz

No math involved here, just a bit of lateral thinking. Can you figure out what comes next? 2, 4, 8, 4, 4, 1, 3, 2, 7, 8, 3, 3, 6, 3, 4, 5... Bonus: How about here? 6, 3, 6, 3, 3, 5, 3, 3, 4...
7
votes
1answer
376 views

What happened to the Fibonacci sequence?

I'm sure you've seen some of these numbers before: 1 3 8 13 21 30 36 45 54 63 Whats the next number in the sequence? And what have I done to the Fibonacci ...
3
votes
1answer
1k views

Missing number in this sequence?

I heard this puzzle in a quiz I participated in: 10, 11, 12, 13, 14, 15, 16, 17, 20, 22, 24, ?, 100, 121, 10000 What is the missing number? (You don't need to do any big calculations, and you ...
1
vote
3answers
493 views

What is the next number in the following sequence?

1, 6, 5, 3, 4, 1, 2, 2, ? Hint: the task is pattern recognition using basic mathematical operations.
17
votes
2answers
1k views

Logically linked numbers

The left and right numbers are linked. What should the last number on the right be, and why? \begin{align} 135759&: 1 \\ 151364&: 4 \\ 255075&: 9 \\ 279422&: 36 \\ 292620&: 91 \\ ...
14
votes
9answers
3k views

Number-sequence puzzle where the number goes down in the middle

My friend asked me for help with an IQ test and after she did it online she came back at me with the ones she couldn't solve. Two of them however, I discovered are the same puzzle type, but no ...
24
votes
1answer
777 views

Oh dear, oh my, how blatant

Looking at the Puzzling Stack Exchange recently, I found a surfeit of number sequence riddles that all look the same! I mean, there's no difference between any of them. I'm sick and tired of all these ...
10
votes
6answers
794 views

A Game Of Cat And Mouse: Part 2

Part 1 can be found here. Information from Part 1 is not required to solve this puzzle. Having identified where El Gato intends to strike next, you charter one of the Bureau's jets and fly off to ...
12
votes
1answer
485 views

Find the next number in this sequence

Find the next number in the sequence : 1; 5; 33; 25; 2; 16; 14; 12; 11; ? What is the next number and why ?
10
votes
2answers
2k views

What is the next number in this sequence? 0, 1, 11.2, 10.2, 113.2, 103, 103.2, 0.2, 1.2, 2.2, 2, …

0, 1, 11.2, 10.2, 113.2, 103, 103.2, 0.2, 1.2, 2.2, 2, ? The only hint I'll give at this stage is that the sequence is infinite. If nobody gets it within a few days, I'll give a few terms that come ...
16
votes
5answers
2k views

Should the angels play their game?

Two angels in heaven want to play a game. One of them comes up with an arbitrary, computable function from the integers to the integers. The other angel has to guess what it is. The second angel can ...
15
votes
5answers
2k views

Important days in history… and to come!

The other day I decided I wanted to come up with another simple puzzle before releasing another toughy on puzzling.SE. I came across an interesting series of dates that I wanted to share and see if ...
12
votes
3answers
2k views

Three different, and somewhat difficult, sequence puzzles

Here are three different letter/number sequences. Try to solve as many as possible. The spoilers give hints to each sequence in the form of how many elements are in the corresponding sequence. ...
8
votes
2answers
423 views

A sequence defined by a single fraction

I have a sequence of numbers here, which follow a very simple rule that can be expressed using a single fraction: 1, 2, 10, 11, 13, 15, 20, 22, 25, 28, ... What is this rule (in particular, what ...
3
votes
1answer
86 views

Number Sequence Series-Question 3

I want to share a series of questions that are created by myself. I will give a hint in 24 hours and my answer in 3 days given that nobody could answer my question. Here is my number sequence: 2020,...
3
votes
1answer
1k views

Alphabet Number Matching

If : 888888 = T 777777 = O 555555 = Y 444444 = R then : 666666 = ? Basically you need to tell the logic along with ...
4
votes
3answers
965 views

A simple but most devious sequence puzzle

This is a question from a previous, now-defunct version of the Temple of Quetzalcoatl, that I've posted here as an exemplar of one of the difficult puzzles you might encounter while solving it. The ...
3
votes
1answer
298 views

Another mathematical number sequence

Can you work out the mathematical rule for this number sequence? 354, 72, 345, 132, 6, 216, 9, 729, 354, 72, 345........ Hint 1 From time to time hints will be updated until solved. Note: this ...
14
votes
2answers
703 views

Can you generate the next number in this integer series and describe the rule?

2, 3, 5, 7, ... 11, 13, 17, ... 25, 29, ... 35, ... 43, 47, 49, ... 53, 59, 61, 65, 67, ... 71, ... ?? The answer (indicated by two question marks) ...
12
votes
1answer
1k views

Really, really, really hard sequence

... in which you have nothing to do with math ... except maybe with some counting and this and that ... but no calculations, no, definitely no. $1, 0, 8, 62, 90, 68, 83, 89, 88, 057, 619, 028, 693,...
10
votes
3answers
648 views

Cryptobiology? Biocryptology?

I have a friend who is a self-proclaimed cryptobiologist. Okay, maybe I don't, but if I did, I like to think she would have presented me with this puzzle: Find the hidden message: 441344•...
9
votes
1answer
336 views

Sequence seen on the street

I was walking on the street when I saw the following numbers: $0, 7, 2, 3, 9$ The sequence continued a bit further then looped back. However, it was not the sequence I was expecting, so it took me ...
8
votes
1answer
717 views

What is the next integer in this sequence?

First, I offer you a little something to put you in the right spirits: For many many years, black cats have had some interesting associations and reputations, which no doubt helped inspire The Black ...
4
votes
1answer
373 views

The Generic Number Sequence Puzzle

If you are in a hurry, you can skip the story below, there's a TL;DR near the end. The gist is that we are going to solve every number-sequence puzzle ever*, all in one go. *: Terms and ...
0
votes
1answer
373 views

A final batch of four sequence puzzles

This is my seventh (and probably last) batch of sequence puzzles that are nasty and hard to solve; I stress that each of them has a clear and justifiable solution. Sequence 1: RC, NU, RT, RS, PI, ...
-7
votes
2answers
361 views

Next number in the following sequence? [closed]

In following sequence, Find the next number? 85, 79, 73, 69, ?
9
votes
1answer
742 views

A sequence about you (Puzzling Stack Exchange users)

I have a mysterious sequence for you... $204, 186, 172, 133, 126, 123, 120, 119, 111, 107, 102, 96, 90, 87, 86, 86, 85, 79, 75, 73, 70, 68, 66, 66, 65, 65, 65, 64, 64, 64, ...$ This sequence may ...
6
votes
1answer
231 views

Number Sequence Series-Question 2

I want to share a question that is created by myself. I will give a hint in 24 hours and my answer in 3 days given that nobody could answer my question. Here is my number sequence: 1441,2882,5764,?,...
6
votes
4answers
183 views

Number Sequence Series-Question 1

I want to share a question that is created by myself. I will give a hint in 24 hours and my answer in 3 days given that nobody could answer my question. Here is my number sequence: 3/2,2/3,3/4,1/3,...
6
votes
1answer
201 views

An ad-hoc number sequence to solve

Inspired by another question here, I thought I might create my own: Fill in the correct number in this sequence: 5, 3, 4, 9, 8, 3, 5, ... And of course, explain why :)
5
votes
1answer
421 views

Next number sequence

Be forewarned: this is a riddle in the spirit of riddles. Given the following: ...4522222222255555555599999999 What are the next digits? Note: I did not specify the number of digits you should ...
4
votes
2answers
248 views

Yet another batch of four sequence puzzles

This is my sixth batch of sequence puzzles that are nasty and hard to solve; yet, each of them has a clear and justifiable solution. Sequence 1: Ca, Cl, ??, Er, ??, Po, Te, Th, ?? Sequence ...
4
votes
2answers
232 views

Two honeycomb hints, part two (find the next number)

Another variant of my previous question, this one might be easier (or harder). What is the next number in the sequence $1, 2,6, 16, ...$? To clarify: the 'hints' are really clues. They are hidden, ...
3
votes
0answers
269 views

Number sequence 5

Fill in the correct number in this sequence: 5 3 8 9 1 27 ? The options are: 18, 54, 38, 14 or 13. I can see the pattern of 3, 9, 27 but other than that I am clueless. Source: a publicly available ...
2
votes
2answers
146 views

An ad-hoc number sequence to solve 2

Continuing on from my last effort, let's try something new. "7, 14, 29, 62, 132," have I, but now what should I do? Which number comes next? Hint - mouseover if you want to see the next number in ...
2
votes
1answer
222 views

When setting number-sequence puzzles, is there any accepted method to prevent arbitrary solutions?

When setting a number sequence puzzle, one normally gives a finite sample and asks for the rule that specifies the members. The sample has to be finite because it's impossible to uniquely specify an ...