Questions tagged [number]
A competition to solve a particular problem through the usage and manipulation of numbers.
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Funny Numbers :D
The task is to calculate the average "funniness" of a given number given the following scoring system:
1 point for each "420" in it
2 points for each "69" in it
3 points ...
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Find the longest permutations of integers from 1..k such that all neighbouring pairs sum to a square
OEIS A090461 details the ‘numbers k for which there exists a permutation of the numbers 1 to k such that the sum of adjacent numbers is a square’. This has also been the subject of Matt Parker’s ...
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Keep jumping till a cycle
Objective
You're on a nonempty list of integers that wraps around. You start at the leftmost entry of the list, and keep jumping to the right to the amount of the integer entry you're at.
Eventually, ...
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American odds to probabilities
American odds (aka moneyline odds) are numbers like \$+150\$ or \$-400\$ used to express how much a winning bet would pay out. Convert odds to a fair win probability like this:
Positive odds \$+n\$ ...
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Add two really big numbers
Preamble
We've already proven we're good at adding two numbers, but many solutions only operate on tiny numbers like 2³²-1, honestly we can do a lot better.
The Challenge
Given two unsigned, non-...
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Half even rounding
The round function in Python 3 will round values of the form \$k+\frac{1}{2}\$ (with \$k\$ being an integer) to the nearest even integer, which is apparently better ...
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Print a meter of numbers to a specified limit
Given a positive integer n, output a number meter formatted like this:
...
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Output the smallest increasing sequence where each term is coprime to preceding 3 terms
This sequence is defined as
Starts with 1, 2, 3
The next element of the sequence is the first number greater than the previous three that is co-prime with each of the previous 3 elements in the ...
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Near miss prime multiples
This challenge was originally posted on codidact.
Given a number \$n \geq 3\$ as input output the smallest number \$k\$ such that the modular residues of \$k\$ by the first \$n\$ primes is exactly \$\...
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Start a program so that /proc/self/cmdline contains a binary representation of the input number
I am sorry for the very long description. But i think some information of how /proc/self/cmdline works and how it can be used to get a integer input was necessary.
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Landmine Number IV
Background
You have again x3 been given the task of calculating the number of landmines in a field. But this time, we have no landmine number, and some landmines have exploded.
You must calculate the ...
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Vanilla Natural Logarithm Challenge
There is a challenge for multiplying two numbers so I guess this counts too
Given as input a positive real number n compute its natural logarithm.
Your answer ...
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Landmine Number II
Background
You have again been given the task of calculating the number of landmines in a field. However, we have now travelled into the flatlands.
You must calculate the landmine score given a list/...
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Landmine Number I
Background
You have been given the task of calculating the number of landmines in a field.
You must calculate the landmine score given a list/string of numbers and the landmine number.
The landmine ...
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votes
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Reversed Squares
Given an integer n, your task is to determine whether it is a perfect square that when reversed, is still a perfect square. You may assume n is always positive.
When numbers such as 100 (10x10) are ...
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Detect Maxima Using Persistent Homology
Inspired by this SO answer about peak detection.
Background
Persistent homology is a fancy term for a fancy math concept, but in this case all we care about is how it can be used for peak detection. ...
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votes
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Last odd digit of power of 2
Task
Given \$n\$, output position of the last odd digit in the decimal representation of \$2^n\$ (counting from the end).
Rules
There are no odd digits for \$n=1,2,3,6,11\$ \$(2, 4, 8, 64, 2048)\$ - ...
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Cube calendar numbers
Credit: Marco Verch CC BY 2.0
A two-cube calendar, as shown in the picture, uses two cubes with digits painted on the faces to display the date. For dates in the range 1-9, a leading zero is used (&...
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How powerful must this e approximation be?
This challenge was inspired by this non-challenge about the natural logarithm base \$e\$ and the following pandigital approximation to \$e\$ appearing on a Math Magic page:
$$\left|(1+9^{-4^{7×6}})^{3^...
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Borders of a Rectangular Matrix
Although it's done a few times as sub-challenge of a larger challenge, and we also have a challenge to remove the borders of a square matrix, I couldn't find a challenge to output the borders of a ...
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Compute cumulative means efficiently
Consider a sorted array of positive floating point numbers such as:
input = [0.22, 2.88, 6.35, 7.17, 9.15]
For each integer \$i\$ from 1 up to the last value in ...
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Add two real numbers ... probably
The problem statement here is pretty simple, take two real numbers on the range [0,1) as input and output their sum, with probability 1.
The catch here is that there are a lot of real numbers. There ...
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The number of solutions to Hertzsprung's Problem
Hertzprung's Problem (OEIS A002464) is the number of solutions to a variant of the Eight Queens Puzzle, where instead of placing \$n\$ queens, you place \$n\$ rook-king fairy pieces (can attack like ...
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Gödel encoding - Part II (decoding)
Part I
Previous part was considered encoding of non-empty nested lists with a positive integer.
Reminding the coding procedure \$G(x)\$:
If \$x\$ is a number, \$G(x) = 2^x\$
If \$x\$ is a list \$[n_0,...
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Gödel encoding - Part I
Related but different.
Part II
Taken from the book: Marvin Minsky 1967 – Computation:
Finite and Infinite Machines, chapter 14.
Background
As the Gödel proved, it is possible to encode with a unique ...
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Zahlen auf Deutsch! (Numbers in German)
Your task is to write a program that receives a base 10 number from 0 to 99 and outputs the German name of that number with non-ASCII characters replaced with ASCII equivalents.
German number names
<...
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How Super is this Prime?
A super prime is a prime whose index in the list of primes is also a prime:
...
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Doors and guards
Related but noticeably different
You are the leader of the guard in the dungeon of an ancient castle.
There are N doors in the dungeon and ...
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Is it a Frog List?
Challenge:
A Frog List is defined by certain rules:
Each frog within a Frog List has an unique positive digit [1-9] as id (any 0...
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Implement the `<=>` three-way comparison operator on numbers
In C++, there exists a a <=> b three-way comparison operator that, for numerical types, does the following:
If a < b, ...
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Generate number from given range
Your function must accept three numbers in any order:
A signed real number (or ±Infinity) - The number (N) for which you have ...
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Imtiaz Germain Primes
Description
"Imtiaz Germain primes" is not a technical name in Mathematics, but my weird creation, in the memoir of the famous mathematician Sophie Germain. These primes can be generated by ...
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Largest Binary Area
Take the sequence of all natural numbers in binary, (1, 10, 11, ..) then write them vertically beside each-other like this (least significant bit on top; 0s have ...
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Multibase Numbers
(Similar: Through the bases)
Normally, our number system is base ten, with the digits 0123456789. However, we can increase or decrease the base count (so ...
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Shortest code to generate all Pythagorean triples up to a given limit
Generate the shortest possible code in any programming language that can generate all Pythagorean triples with all values not exceeding a given integer limit. A Pythagorean triple is a set of three ...
- 1,732
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Consolidate a 6-axis 2-dimensional Vector
Typically, when we want to represent a magnitude and direction in 2D space, we use a 2-axis vector. These axes are typically called X and Y:
This isn't always convenient, however. The game BattleTech ...
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Summing the Digits of a Number
Challenge
Given a non-negative integer, find the sum of its digits.
Rules
Your program must take a non-negative integer as input.
Your program should output the sum of the digits of the input ...
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Whole Number Groups
Given a list of fractions, group them so that each group sums to a whole number. This should be done in such a way to maximize the number of non-empty groups.
You may assume a solution exists. Order ...
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Number Clusters
Your task is to create a program or function, that when given an input list of nonnegative integers of length \$l \ge 2\$ and a nonnegative integer \$c\$ where \$2 \le c \le l\$, group the list into \$...
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Find opposite string
Your function must accept one string and return the opposite
The opposite string is a string where all characters go in reverse order, all letters are replaced with the opposite mirror letter from the ...
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Print all pandigital numbers
Given a base as input, output all pan-digital numbers. A number is pan-digital if it includes every digit in that base at least once, possibly multiple times. Every number is considered to contain an ...
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Sum of numbers of arbitrary length
Your function must accept 2 strings which are correct numbers. It needs to sum them up (without rounding and floating point errors) and return the result (which is also a correct number) without any ...
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Sum of Consecutive Squares
Your task
Given a integer input, \$ n \$ (such that \$ n > 1 \$), decide whether it can be written as the sum of (at least 2) consecutive square numbers.
Test cases
Truthy:
...
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Create a bingo card generator
Bingo
Bingo is a numbers game where players match randomly drawn numbers to the numbers on their cards. Each bingo card is a square grid with 25 spaces, and the columns of the grid are labeled with ...
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Shortest digid-app GetPercentageRounds function
Context
So the Dutch "Ministerie van Binnenlandse Zaken en Koninkrijksrelaties" (NL) - "Ministry of the Interior and Kingdom Relations" (EN) recently released the source code of ...
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Toggle some bits and get an actual square
Inspired by the title of the Toggle some bits and get a square challenge.
In that challenge you output how many bits should be toggled, in order for the base-10 representation of the binary to become ...
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Form a subset that is a continuous range
Given a list of lists of positive integers, output a subset of them so their union forms a continuous non-empty range with no numbers missing. For example, consider this input:
...
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Find the first run of numbers summing to n
Given as input a positive nonzero integer n >= 10 and a sequence of digits 0-9 (which may be taken as a string or a list), ...
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Division between two strings
Inverse function of this challenge
To (properly) multiply an string by an integer, you split the string into characters, repeat each character a number of times equal to the integer, and then stick ...
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Round to nicer numbers
The standard way to round numbers is to choose the nearest whole value, if the initial value is exactly halfway between two values, i.e. there is a tie, then you choose the larger one.
However where I ...
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