Questions tagged [number-property]
Puzzles that use number properties such as even and odd, multiples of numbers, part of a well-known sequence (i.e. Fibonacci) or theorem (Pythagorean relations) or others in part of the method to solve the question.
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Can you find the missing letters?
A pattern of letters has had letters 10 through 20 deleted. Your job is to find out what letters should go in spots 10-20. Here is the pattern:
a, b, c, d, d, d, f, e, f, _, _, _, _, _, _, _, _, _, _, ...
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What do 84, 96 and 108 have in common?
There's a certain property that's shared between (as far as I know) infinite positive integers including 84, 96 and 108. Below are the first thousand numbers with this property; I added that many in ...
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How many does 4 have?
I found out that
0 has none
1 has one
2 has two
but 3 has none
How many does 4 have?
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If ABCDE*4 = EDCBA. A,B,C,D and E are all natural numbers ( 1-9) without repeating any natural number. Why is it deducible that E cannot be three?
If ABCDE*4 = EDCBA. ABCDE,EDCBA are five digit numbers. A,B,C,D and E are all natural numbers ( 1-9) without repeating any natural number. Why is it deducible that E cannot be three?
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Which positive integers have at least one positive integer multiple such that the base 10 representation of that multiple has only even digits?
Which positive integers N have the property that there exists at least one positive integer multiple of N such that the base 10 representation of that multiple has only even digits?
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This poem is titled Ζ-Gap
The answer is a two-digit number.
Do whatever you want to play
Solution is one step away
Mine for alien harmony
Take some notes you want to declare
Regions you were so unaware
Fundamental is always ...
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Pick the odd one out: 214, 350, 520, 738
I am preparing for an exam(NTSE), and I came across this puzzle(aptitude) in one of the quizzes. book(study guide NTSE). The book's author is Arihant Experts.
The question is to Pick the 'odd one out' ...
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Pick the odd one out: 146, 821, 704, 603 [closed]
I am preparing for an exam, and I came across this puzzle(aptitude) question.
The question is to Pick the 'odd one out' and there are four options given.
146, 821, 704, 603
The correct answer is 603....
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Digital Digits Magic Square 3x3 that can be rotated 180 degrees
In the below image we have a magic square of a size 3x3. The magic number for all its rows, columns and both diagonals is 165.
Rotate the grid 180 degrees and all sums still have the magic number 165. ...
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A Weird Sequence
Today, I was in Rome for a vacation. The most peculiar thing happened. A gnome walked up to me. Uttering no words, it handed me a slip of paper.
0, 1, 1, 2, 3, 2, 5, 5, 5, 9, 4, ?
Naturally, I was ...
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How many combinations can you make with 3 digits?
So my mom- a teacher - called me and my brother and gave us each a paper and pencil.
She said: Think of three distinct single digit positive integers (0 to 9) and write down as many numbers (number ...
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Consider the equation a?b?c =d [closed]
Consider the equation a?b?c =d.
Here a, b and c are 3 distinct integers from 0 to 9 (both inclusive) and "?” represents any
signs out of “+", "-", “x” of “÷”. Note that the 2 ...
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What is a Good Pasta Number™?
This puzzle is inspired by JLee's What is a Word/Phrase™ series and the subsequent "Number" variants. (Actually, I'd originally tried to create a more original puzzle using the same idea, ...
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I wonder what that would be
This is my own puzzle.
Consider the following
Alice begins march for peace in East Bengal along with Gandhi
Bentley celebrated the first Bahia Independence Day
Catherine saw the starting of the Great ...
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How can four be the half of five? [closed]
I came across this enigmatic one-liner:
How can four be half of five?
Can you figure it out?
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What is a Chess Number™?
This is in the spirit of the What is a Word/Phrase™ series started by JLee with Number version puzzles.
If a number conforms to a special rule, I call it a Chess Number™.
Use the following examples ...
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Fractions and Fractional Numbers
Using fractions and fractional numbers of the digits $1$ to $10$ and only the mathematical operations of addition, subtraction, multiplication, and division, including parenthesis (e.g. $1 + 2 - (3 * ...
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Consecutive integers which have digital sums that are not relatively prime
What are ten smallest natural numbers n, such that n and n+1 have digital sums which are not relatively prime?
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What number comes next in this evenly doubled sequence?
I've been playing around with sequences lately and found a pretty evenly doubled sequence of single digit numbers:
1, 12, 30, 64, 65, 156, 175, 368, 369, 371, 752, 753, 1524, 1525, 3060, 3073, 6168, ...
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An oddly formed sequence?
I've been playing around with sequences lately and came across one that was rather, odd.
$101$, $123$, $147$, $189$, $191$, $213$, $217$, $279$, $...$
Hints
Let $N_i = 101$...
Can you determine the ...
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A dance between numbers
Given the following equation:
$$\Delta = \Biggl(\frac{t \mod 6}{(t \mod r) + 1}\Biggr)^2$$
Find the relationship between $t$ and $r$, along with the properties of each, that ensures $\Delta = 9$. For ...
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The maze of everlasting flowers
You were recently caught trespassing on the queen's hunting grounds. The punishment for this crime is a miserable experience the locals call the maze of everlasting flowers:
The full resolution of ...
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Scrabble with prime numbers!
How to Play
Overall, gameplay is very similar to typical Scrabble; however, unlike typical Scrabble, you'll be using digits instead of letters (we'll cover your tile bag later). The objective is to ...
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The digits of the cube of a 3-digit number X
The digits of the cube of a certain 3-digit number X are, from left to right, the square of a 2-digit number, followed by the square of another 2-digit number, followed by one digit. (Everything is ...
user76726
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Integers containing all ten digits
It is known that most positive integers contain at least one copy of each of the ten digits.
What is the largest n such that at most 50% of the integers in the set [1,2,3,...,n]
contain at least one ...
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Mapping days as a 4 digit number! [closed]
I have a puzzle that includes mapping days as a 4 digit number.
Sunday: 6137
Monday: 6240
Tuesday: 7358
Wednesday: 9497
Thursday: 85??
The first digit is just the number of characters and the second ...
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The largest Saturday number
No weekend love yet shown, therefore I will fix that.
A Saturday number is a number in which for all $1 \le i \le l$, where $l$ is the length of the number, the first $l$ digits (from the left) divide ...
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Largest number with no repeating digit pairs
What is the largest whole number that you can form, such that no pair of consecutive digits occurs more than once? For example you can have 34543, but you cannot have 34534 as the pair "34" ...
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Adding up divisors of integers
Alice and Bob play a game, taking turns. Alice starts and writes an integer between 1 to 10 on a blackboard.
Then Bob adds any integer between 1 to 10 to this number and writes it on the blackboard.
...
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Making a 10 digit number divisible by 3
Alice and Bob play the following game, taking turns. Alice starts and writes a single digit from 0 to 9 at the blackboard.
At every turn, each player adds a single digit at the right of the current ...
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What number goes in the ?? box?
A simple pattern puzzle
What is the number in the ?? box? Why? No programming please.
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Odd numbers to Even numbers
Remember the old puzzle?
"Can you take just one letter out of an odd number and make it even?"
Note the clever wording. It just says make it even; not "make it an even number"...
...
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Largest 5-digit palindrome in base 16, where each digit appears at most twice
What is the largest number $ x $ such that $ x_{16}, $ i.e. $ x $ in base 16, is a 5-digit long palindrome, where each digit appears at most twice? A palindrome is a number that reads the same forward ...
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When should this question be answered?
If you hover your mouse over the time marked in the right-bottom corner of this post, then you will see a string showing the exact time that I post this question, which reads ...
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What is the house number in nolteight street
Alice moved to nolteight street. Bob meets her after her move, and he knows that the smallest house number in nolteight street is 8, and the highest number is 100. But he does not know Alice's house ...
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Consecutive integers with digit sum divisible by 19
What is the smallest positive integer N, such that the digit sum of N and N+1 are both divisible by 19?
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A function. Really?
If you give me a 5, I give you a 21.
If you give me a 6, I give you a 2.
If you give me a 7, I give you a 12.
If you give me a 10, I give you a 101.
What am I processing to get the result?
Hint 1
...
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When do decimal-coded binary numbers XOR to zero?
Background definition: XOR on numbers
Given two non-negative integers $x$ and $y$, let $x\oplus y$ denote the bitwise exclusive or (XOR) of the numbers $x$ and $y$. This is the result of writing $x$ ...
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Sort 10 clock numbers
An electronic clock shows hours and minutes: from 00:00 to 23:59.
Sort the numbers 0, 1, ..., 9 according to the time of their presence on the clock board during the 24-hours.
Edit
For example, for ...
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What is so unique about these four numbers?
These four numbers look like four ordinary numbers. But I found something unique about these four that I may be only true for one other set of numbers-- unless you raise the bar-may be.
So what is ...
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100 lightbulbs in a room [duplicate]
There are 100 lightbulbs in a room, each with it’s own switch in the off position (all lightbulbs work and start off, no funny business). There are also 100 people numbered from 1 to 100 standing ...
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Welcome to the Acme Corporation - please find your floor number
Welcome to the Acme Corporation.
The Acme Corporation is the greatest company in the world, and it should be your utmost honor and privilege to be employed as an associate of the Corporation.
The ...
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After the funeral
The mood was sombre in the lawyer’s office. Eight members of the Picodie family gathered together to hear the reading of their recently deceased father’s will. Around the table sat Eli, Ron, Agnes, ...
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Lawbreaking by the numbers
Special Agent Benford has been stymied by a third unsolved case of
miscreant creative accounting and will voluntarily retire
from the Fraudulent Numbers Task Force.
Benford’s ability to detect ...
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Numbers with a shared property
The following numbers share same property.
What are the next two numbers with same shared property?
What are the previous two with the same shared property?
What is the largest three digit number with ...
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How many pigeons are in the flock? [closed]
A crow reaches a flock of pigeons. the crow asks the pigeons' leader: "How many of you are there?"
The pigeon replies: "We and we and a half of we and a fourth of we and you equal 100.&...
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The number game
There is a number,
the second digit of which is smaller than the first digit by $4$, and if the number was divided by the digits' sum, the quotient would be $7$.
What is this number.
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What is the secret operator?
There is a secret operator $F$ that takes two whole numbers and outputs a new number. For example
$$\begin{split}F(6,9) &= 15\\
F(66,11) &= 110 \\
F(86,18) &= 179\end{split}$$
Can you ...
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What is a Trinity Number™?
This is inspired by the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles, and the Number™ series.
If a number conforms to a special rule, I call it a ...
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Dead By Daylight
This puzzle is a reference to a game, Dead By Daylight. Though you don't need a knowledge about the game. Consequently, there is no "video-games" tag.
Story
The Entity wants to have the ...
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