Questions tagged [number-sequence]

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

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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 ...
51
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6answers
4k views

What makes an Interesting Puzzle™?

This puzzle is based off the What is a Word™ and What is a Phrase™ series started by JLee and their spin-off What is a Number™ series. I like What is an Adjective Noun™ puzzles. Here are a few I ...
49
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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
38
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2answers
3k views

It's my birthday

Just like last year, my age is a number you can score with one dart. The year before that, it wasn't, and it won't be next year. How old am I?
36
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5answers
6k views

A very simple puzzle: 1,1,2,1,2,2,3

Here's a simple puzzle, I know that you will find. As long as you can count, It shouldn't take much time. 1 1 2 1 2 2 3 1 2 2 3 Find the next 4 numbers in this sequence.
33
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2answers
2k views

A powerful drink

I'm addicted to this stuff. I had my first double when I was 16. There were five of us that night on the town. I didn't think much of it then, but two years later I had another double, and then ...
32
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2answers
3k views

Ancient machine in the desert… how does it generate its output?

I was walking through the desert and came across an ancient contraption of cogs and gears. It had a series of dials on one side that appeared to allow the input and output of numbers. On the other ...
31
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1answer
2k views

Professor Halfbrain and the sum of the digits of all divisors

Yesterday I met professor Halfbrain in the city. The professor looked tired and somewhat exhausted. He told me that he had spent his nights and days with adding up digits of divisors of positive ...
28
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1answer
2k views

That gap is a bit jarring

... but there doesn't seem to be anything missing. $0,1,2,3,4,5,6,7,1527465$ What then could cause that rather large gap?
26
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5answers
4k views

An unusual and very hard number sequence problem

I heard this number sequence problem about 25 years ago from a maths lecturer. What number should go in the place of the question mark in this mathematical sequence: $..., 30, ?, 60, 90, 140, 225, ...
26
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3answers
974 views

Why aren't the numbers playing nicely anymore?

The natural numbers have gotten in a big fight and split up into groups. If we can't get them back together again, the universe may never be the same! What kind of sense does it make to have three ...
25
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2answers
20k 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 ...
25
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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 ...
24
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1answer
778 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 ...
23
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1answer
2k views

A brief int counter

The following infinite sequence is used by those taking first steps in maths. 3, 3, 4, 4, 4, 3, 4, 5, 3, 3, 4, 5, 6, 7, ? Find the next number.
22
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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 ...
22
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1answer
1k views

Revenge on OEIS*

First, a story about how I messed up a puzzle: It’s hard to make a simple yet creative number puzzle. After fiddling one late, dark winter evening with different patterns, at last I made a sequence ...
20
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2answers
1k views

What is a RAP Number™?

Taking inspiration from "What is the word™" series, here the numbers conforms to a special rule, I call it a RAP number™. Use the following examples below to find the rule. Note : This is my first ...
19
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2answers
2k views

Ernie and the Alien Invasion

Yesterday I dropped in on Ernie to show off my new j-watch. Ernie wouldn't be impressed by instant wrist-mounted access to social media sites like me-tube, tweeter and farce-book so I thought I would ...
19
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5answers
749 views

A riddle that has been killing me the whole day

So I'm walking around in London and found the following number riddle. The rules say, that what ever pattern you find, must be true for the rows as well as the columns. The answer in level 1 is for ...
18
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1answer
1k views

How does this addition work (13+7=1130)?

I found this problem on 9gag and I have no idea how to solve it. Here is the question: $13+7=1130$ $88+9=47$ $32+28=2530$ $10+999=1149$ $444+77=61$ $55+111=56$ $21+0=1221$ $7+22=39$ $33+5=38$...
18
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1answer
1k views

What kind of puzzle is solved by these sequences of numbers?

Samantha had been fiddling with something at her desk for ages, and constantly scribbling notes on a piece of paper. When my curiosity eventually got the better of me, I wandered over to ask what she ...
17
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2answers
1k views

What does this group of numbers represent?

How is this set of 8 numbers - $6, 8, 15, 20, 36, 48, 90$, and $120$ - derived? I could provide hints but it would make it too easy.
17
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3answers
940 views

How is this number sequence built up and how does it continue?

Can you work out how this number sequence is built up? Can you work out how it continues? 1, 1, 2, 4, 8, 20, 60, 240, 1500, ....... Hint 1 Hint 2 From time to time hints will be updated. Note: ...
17
votes
1answer
701 views

Quality Over Quantities

Your final answer will be a number (or maybe not?) 6.1482925535194332784626433, 15, 70, 5388440228181184467208035634811703511875, 45, 1207432478148385373947988/38313917, 15, 70, ?
17
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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 \\ ...
17
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1answer
386 views

Some enigmatic number sequences

Here are some numbers: 959, 233, 14, 36, 105, 45, 784, 120, 1579, 1001, 1111, 90, 841, 1607, 590, 625, 609, 144, 606 And here are the rest of the numbers: 1, 2, 5, 20, 30, 34, 42, 55, 56, 66, 72, 78, ...
17
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1answer
956 views

Creepy video on Youtube, with secret cipher built in

This showed up in r/deepintoyoutube: https://www.youtube.com/watch?v=j1ExfbH4Jew I've posted it around, and no one has solved it. I believe it is a cipher for a couple of reasons, at the end 26 ...
16
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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 ...
16
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1answer
2k views

Can you find O in this math riddle?

If: R = 1,111 T = 2,222 E = 3,333 N = 4,444 What is O equal to?
16
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1answer
1k views

Given these numbers, find the secret word

My son is 12 years old and his task was to find an English word from these numbers: 13; -8; 2; 2; -6; 12; 2; 6; -1; -12 where ...
16
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5answers
1k views

Sequence puzzle

This is a sequence puzzle I found online which I'm stuck on: 452801, 773924, 102410, 471056, ? I figured out how to get from the first number to the second (+3, +2, +1, +1, +2, +3) for the digits, ...
16
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1answer
665 views

Sorcery squares!

The following 5-by-5 squares of digits are not magic squares, but nevertheless they each have a crucial property which enabled me to generate them. What is that property? How could you generate more ...
15
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9answers
5k views

Is this sequence that hard?

I published a sequence that seems difficult to the general public, so I've thought of posting it here. It has a very simple logic (language independent). Can you figure out the next number?
15
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8answers
2k views

Next number in sequence, understand the 1st mistake to avoid the 2nd

31 30 31 30 31 31 30 31 30 31 31 __ ? Some of you said the 10th number would be 21, not 31. Almost all of you were aware of this wrong answer, even if you knew it was ridiculous! Some of you will ...
15
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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 ...
15
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3answers
630 views

Mathematical cryptic clues

Programming language, after removing loss for you, reverses time (6) Complex arithmetic begins, Turing tests start beforehand (7) Quadruply male doctor Einstein, familiarly (11) Lie on a ...
15
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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 ...
15
votes
1answer
475 views

What is a Well-toned Number™?

This puzzle is based off the What is a Word™ and What is a Phrase™ series started by JLee and their spin-off What is a Number™ series started by smriti. If a number conforms to a certain rule, I call ...
14
votes
3answers
1k views

A Simple Number Sequence

What would be the next digit that follows these numbers? 1, 11, 20, 30, 7, 49, 42, 23, 3, ? Just so it's clear, you won't need any mathematics to solve this at all! In fact, everything you ...
14
votes
1answer
1k views

Name These Animals

Can you definitively name these animals? More importantly, can you find and extend the hidden number sequence? With elegant, long ears, precious huge animals need to be protected. Winter predator ...
14
votes
1answer
508 views

250 Floor Tower

There's a tower in a far off land, one that you can only climb by unlocking the secret password to all the floors. Each floor has an inscription on the walls, indicating a number. As you approach a ...
14
votes
2answers
715 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) ...
14
votes
1answer
1k views

Number Pie Chart

What should be the missing number?
14
votes
1answer
337 views

What's up with my calculator?

As I am wont to do, I got a new calculator the other day. Obviously it needed a few test calculations: 5 + 6 = 11 22 - 17 = 5 10 + 3 = 13 4 * 6 = 24 OK, so ...
14
votes
1answer
543 views

This is NOT a number sequence puzzle

Since everyone is trying their hand at this type of puzzle, I've decided to create a number seq - We interrupt your Puzzle Solving Entertainment to inform you of this Public Service Exclamation: ...
14
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3answers
1k views

Logic behind numeric sequence

There was this sequence on a magazine and the reader has to find the next number: 10, 2, 4, 6, 2, 8 I couldn't find one, then I found the answer in the next magazine. They say the number is 5, so ...
13
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2answers
2k views

What's the next number and why?

What's the next number and why? 1,602,817,493,294,902
13
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3answers
893 views

Finding Sequence in Third Square

This particular puzzle is throwing me off for some reason, given that solutions I've tried for similar problems are not working. Problem Given that you have this square: ...
13
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3answers
2k views

What is the 30th number in the sequence?

What is the 30th number in the following sequence? 0, 2, 4, 12, 8, 20, 24, 56, 16, 36, ... I'm not sure what would be good hints, or how much further out I should list the sequence. I figure the ...