# 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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### this puzzle is based

This message is a basic numeric substitution cipher. The key is the standard, regular alphabet in the correct order (ABC...XYZ). Here is the message: 3 16 15 7 20 1 22 23 13 1 22 10 16 15 21 27 16 23 ...
1 vote
96 views

### 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, _, _, _, _, _, _, _, _, _, _, ...
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. RAP number™ NOT ...
769 views

### 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 ...
662 views

### 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?
230 views

### 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?
151 views

### 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?
525 views

### 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 ...
1k views

### 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 ...
340 views

### 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' ...
211 views

### 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....
648 views

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 ...
1k views

267 views

### 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 ...
322 views

### 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?
238 views

### 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, ...
412 views

### 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 ...
1 vote
173 views

### 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 ...
325 views

### 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 ...
1k views

### 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 ...
631 views

### 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 ...
191 views

### 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 ...
2k views

### 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" ...
185 views

### 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. ...
1k views

### What number goes in the ?? box?

A simple pattern puzzle What is the number in the ?? box? Why? No programming please.
229 views

### 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"... ...
120 views

### 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 ...
2k views

### 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 ...
462 views

### 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 ...
1 vote
259 views

### Two-column table of numbers from a geocaching site

I found this table, but can't seem to find any relation between the numbers. Also there is not much logic involved. 2002 13 1987 11 1984 5 1998 6 2004 22 1999 12 ???? ?? A table with numbers. ...
172 views

### 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 ...
480 views

### 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?
148 views

### 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 ...
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 $x$ ...