# Questions tagged [number]

This challenge is intended to be solved by using, manipulating, accepting as input, or outputting numeric values.

1,009 questions
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### Amount of permutations on an NxNxN Rubik's Cube

Introduction: A 3x3x3 Rubik's Cube has $43,252,003,274,489,856,000$ possible permutations, which is approximately 43 quintillion. You may have heard about this number before, but how is it actually ...
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### Maximum summed subsequences with non-adjacent items

Introduction: Inspired by these two SO questions (no doubt from the same class): print the elements in the subarray of maximum sum without adjacent elements java and Maximum sum of non adjacent ...
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### Divide one number by another

Challenge Given two numbers, output their quotient. In other words, integer divide one number by another. Both divisor/dividend will be under 10001. Division must be performed using integer division,...
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+100

Challenge: Input: A list of distinct positive integers within the range $[1, \text{list-size}]$. Output: An integer: the amount of times the list is riffle-shuffled. For a list, this means the ...
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### Is it a Chen prime?

A number is a Chen prime if it satisfies two conditions: It is prime itself Itself plus two is either a prime or a semi-prime. A prime is a number where it has exactly two divisors and those ...
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### Print all lexicographically increasing numbers under 10000

A lexicographically increasing number is an integer whose digits are in strictly increasing order. Print all lexicographically increasing numbers under 10000. Here are lines of the expected output: ...
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### Is it a Cyclops number? “Nobody” knows!

Task: Given an integer input, figure out whether or not it is a Cyclops Number. What is a Cyclops number, you may ask? Well, it's a number whose binary representation only has one ...
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### List of Python versions

Python is the fastest-growing major programming language today. It is the most wanted language for the third year in a row, meaning that developers who do not yet use it say they want to learn it. [1]....
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### Area of a 2D convex hull [closed]

You are given an array/list/vector of pairs of integers representing cartesian coordinates (x, y) of points on a 2D Euclidean plane; all coordinates are between −104 and 104, duplicates are allowed. ...
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### Sort a number's divisors by prime factorization

Given an input of an integer ≥ 2, output a list of its divisors sorted by the exponents in their prime factorizations, in ascending order, ordering first by the largest prime, then by the second ...
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Everyone knows the Fibonacci sequence: You take a square, attach an equal square to it, then repeatedly attach a square whose side length is equal to the largest side length of the resulting rectangle....
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### Largest number in ten bytes of code

Your goal is to print (to the standard output) the largest number possible, using just ten characters of code. You may use any features of your language, except built-in exponentiation functions. ...
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### No strings (or numbers) attached

If you like this, consider participating in: The Official Dyalog APL 2016 Year Game The monthly Dyalog APL 2017 Code Golf Challenge Make 12 snippets/expressions, in the same language, that result in ...
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### Match Roman Numerals

Challenge Given some input string, return a truthy value if it represents a correct roman numeral between 1 (=I) and 3999 (=...
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### What are the five most powerful characters in your language?

Choose any five characters your language supports. There are 5! = 5×4×3×2×1 = 120 ways these can be arranged into a 5-character string that contains each character once; 120 ...
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### Fibonacci function or sequence

The Fibonacci sequence is a sequence of numbers, where every number in the sequence is the sum of the two numbers preceding it. The first two numbers in the sequence are both 1. Here are the first ...
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### How long does it take to type this?

Introduction I can type at a moderate pace, using the QWERTY keyboard layout. But if a word like yellowwooddoor has a ton of repeated letters, it takes a bit longer to type it. Even worse is when a ...
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### Print all integers

Write a program or function which will provably print all integers exactly once given infinite time and memory. Possible outputs could be: ...
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### New Order #1: How does this feel?

Introduction Putting all positive numbers in its regular order (1, 2, 3, ...) is a bit boring, isn't it? So here is a series of challenges around permutations (reshuffelings) of all positive numbers. ...
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### Sums of prime factors

2013 has the prime factorization 3*11*61. 2014 has the prime factorization 2*19*53. An interesting property regarding these ...
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### Expand and Contract

Take a positive integer $k$ as input. Start with $n := 1$ and repeatedly increase $n$ by the largest integer power of ten $i$ such that $i \le n$ and $i + n \le k$. Repeat until $n = k$ ...
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Introduction: I saw there was only one other badminton related challenge right now. Since I play badminton myself (for the past 13 years now), I figured I'd add some badminton-related challenges. ...
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### Valid term from quadratic sequence?

You are given four numbers. The first three are $a$, $b$, and $c$ respectively, for the sequence: $$T_n=an^2+bn+c$$ You may take input of these four numbers in any way. The output should be ...
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### Interleave numbers from 1 to n, with the same numbers reversed

A simple one: Take a positive integer n less than 1000, and output the integers from 1 to n interleaved with the integers from n to 1. You must concatenate the numbers so that they appear without any ...
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### Rearrange a number into alphabetical order

Given a non-negative integer (n), create a function that returns n in alphabetical order, according to the literal spelling of ...
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### Multiply two numbers

Input: Two decimal integers. These can be given to the code in standard input, as arguments to the program or function, or as a list. Output: Their product, as a decimal integer. For example, the ...
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### Sort a list and write some English!

Your boss managed to read the secret hidden message. He didn't end up firing you, though, he just made you a secretary and forbade you from writing code. But you're a programmer. You need to write ...
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### Upper or Lower Wythoff?

First, let's talk about Beatty sequences. Given a positive irrational number r, we can construct an infinite sequence by multiplying the positive integers to r in order and taking the floor of each ...
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### Back to the Basics of Math

Introduction: We all know these three basic arithmetic math tables I assume. ...
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### Closest 7-Distinct-Prime Product

(via chat) The OEIS entry A123321 lists the sequence of numbers that are the product of seven distinct primes. For brevity, we'll call this a 7DP number. The first few numbers and their corresponding ...
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### Calculating total slots

Given a list of jobs, which must be done in order, with each taking a slot to do, how long will it take to perform them all if after doing a job the same job cannot be done for the next two slots (...
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### Am I not good enough for you?

Background: The current Perfect Numbers challenge is rather flawed and complicated, since it asks you to output in a complex format involving the factors of the number. This is a purely decision-...
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### Fractal Smoke Sequence

Introduction A229037 has a quite intriguing plot (at least for the first few terms): There is the conjecture, that it might indeed have some kind of fractal property. How is this sequence ...
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### Sum integers in a string

Input A string. Output The sum of all integers in the line. Constraints 1≤Length of line≤500 Sample test Case Input the 5is 108 seCONd4 a Output ...
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### Stay away from zero

Task Given a non-negative integer n, output 1 if n is 0,...
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### Generate any random integer

Your program/function should output exactly one integer output any integer with positive probability output an integer greater than 1.000.000 or less than -1.000.000 with at least with 50% ...
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### The Digit Triangles

Challenge: Input: A positive integer $n$ Output: Create a list in the range $[1,n]$, and join it together to a string (i.e. $n=13$ would be the string ...
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### Count up forever

Write a program that counts up forever, starting from one. Rules: Your program must log to STDOUT or an acceptable alternative, if ...
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### Find the number in the Champernowne constant

Introduction In base 10, the Champernowne constant is defined by concatenating representations of successive integers. In base 10: 0.1234567891011121314151617... ...
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### Convert number to a base where its representation has most “4”s

Inspired by this. There is a number, given as either integer, string or array of digits (your choice). Find the base in which the representation of the number will have most "4"s and return that base. ...
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### Print the amount of ones in a binary number without using bitwise operators

Description Given a number, print the amount of 1s it has in binary representation. Input A number >= 0 in base 10 that ...
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### Am I a Rude Number?

For a while now, I've been running into a problem when counting on my fingers, specifically, that I can only count to ten. My solution to that problem has been to count in binary on my fingers, ...
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### Make a (somewhat) self-referential string

You want to make a string where the (1-indexed) character at index n is n. When n is less ...
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### Codegolf Rainbow : Draw in Black-and-White

Introduction: (Source: Wikipedia) When we look at a rainbow it will always have the colors from top to bottom: Red; orange; yellow; green; blue; indigo; violet If we look at these individual rings, ...
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### Is this number a prime?

Believe it or not, we do not yet have a code golf challenge for a simple primality test. While it may not be the most interesting challenge, particularly for "usual" languages, it can be nontrivial in ...
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### As Easy as One-Two-Three

Write a program or function that takes in a positive integer. You can assume the input is valid and may take it as a string. If the number is any of ...
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### Sort a list of Numbers as letters [closed]

So, you have a random list (random meaning it doesn't matter what order it is in) of numbers with a length of n, where n is a positive integer smaller than 1000 and ...
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### Print the nth prime that contains n

This question will be a twist on finding the nth prime number. Challenge You must write a program that will take one input n, ...
Input: An integer $n$, which is guaranteed to be $\ge3$. An integer $d$, which is one of $[-1,0,1]$. Output: A road of size $n$, which will be in a north-west direction if $d=-1$; a ...