Questions tagged [number-sequence]

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

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56
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 ...
54
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4answers
9k 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
52
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6answers
5k 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 ...
38
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3answers
2k views

What comes next in the sequence?

My roommate has insomnia so he was counting sheep to help him sleep. He started with $2986$, then continued with $47786,\ 764586,$ and $12233386$. What sequence is he following, and what was the ...
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?
37
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5answers
8k 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.
37
votes
3answers
7k views

What is the next number in the series: 21, 21, 23, 20, 5, 25, 31, 24,?

I came across a puzzle from a workbook for primary school students who wish to sit in exams for enrolling to selective high schools, which asks about what is the next number in the series. What ...
36
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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 ...
33
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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 ...
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 ...
29
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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?
28
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5answers
6k 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
994 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
24k 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 ...
25
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1answer
807 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 ...
21
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2answers
2k 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 ...
20
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2answers
499 views

A real time-waster: the clock of confusion and color

John was doing his math problems like a good child one day until he looked at the clock to see if it was time to sleep. To his dismay, the blasted thing had become another math problem! But this one ...
19
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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 ...
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
764 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: $13+7=1130$ $88+9=47$ $32+28=2530$ $10+999=1149$ $444+77=61$ $55+111=56$ $21+0=1221$ $7+22=39$ $33+5=38$...
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
975 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
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2answers
1k views

A geometric sequence using one digit

Give the first few terms of a geometric[1] sequence such that: the sequence is increasing and infinite only one digit is used throughout the sequence the terms are written as base ten ...
17
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2answers
678 views

16 number puzzles on a blackboard

I have left you some number puzzles on the blackboard. Solve them and let me know what they spell. Hint:
17
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1answer
714 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
votes
1answer
426 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
1k 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

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 ...
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
1k views

Find d this ones stumped me help?

This one is annoying me so much. Got this from a maths teacher.
16
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3answers
704 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 ...
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
671 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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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
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2answers
749 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) ...
15
votes
1answer
490 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 ...
15
votes
1answer
580 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

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

Explain the number sequence and predict the next 6 numbers

Given the number sequence 0,1,4,9,0,1,9,1,4,2,1,3,0,4,1,5,4,6,9,7,0,9,9,a,4,?,?,?,?,?,? the challenge is to Determine the value represented by a Predict the next 6 entries represented by ? Note ...
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 ...

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