# Questions tagged [number]

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

999 questions
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### Seqindignot sequence

Title is made up, from 'Sequence Index Digit Not'. Challenge: Given an integer n which is >= 0, output the ...
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### Output all distinct permutations of a vector

Challenge: Output all distinct permutations of a, potentially long, list of positive integers. You may assume that the vector has less than 1,000 numbers when testing, but the process should in ...
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### Pick-flatten a list

Consider the process of "picking" a nested list. Picking is defined as follows: If the argument is a list, take an element from the list at random (uniformly), and pick from that. If the argument is ...
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### Bijective function ℤ → ℤⁿ

It is trivially possible to create a bijective function from $\mathbb{Z}$ (the set of all integers) to $\mathbb{Z}$ (e.g. the identity function). It is also possible to create a bijective ...
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### Find the unique twins

You will be given two Arrays / Lists / Vectors of non-negative integers A and B. Your task is to output the highest integer N that appears in both A and B, and is also unique in both A and B. You ...
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### How many Latin Squares?

A Latin Square is a square of size n × n containing numbers 1 to n inclusive. Each number occurs once in each row and column. An example of a 3 × 3 Latin Square is: ...
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### Levenshtein distance & OEIS (Robbers)

This is the Robber post. The Cop post is here. Your task is to take an integer input N and output the Nth digit in the sequence OEIS A002942. The sequence consists of the square numbers written ...
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### Levenshtein distance & OEIS (Cops)

This is the Cop post. The Robber post is here. Your task is to take an integer input N and output the Nth digit in the sequence OEIS A002942. The sequence consists of the square numbers written ...
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### Concatenative counting

Your challenge is to write N snippets of code such that, when you concatenate the first K ≥ 1 together, they produce the number K. The higher N, the better. Here's the catch: you may not use any ...
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### Smallest Zeroless Base

Given a positive integer n, output the smallest base b >= 2 where the representation of n ...
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### Implement the iOS 11 Calculator

iOS 11 has a bug that makes the result of 1+2+3 to be 24. This is related to the animation speed, but anyway: The task is to make 1 + 2 + 3 == 24. But only that. ...
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### Am I a golfy array?

Definition and Rules A golfy array is an array of integers, where each element is higher than or equal to the arithmetic mean of all the previous elements. Your task is to determine whether an array ...
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### Triangular Numbers

(no, not those ones) The Challenge You'll be given two inputs. The first is a positive integer n > 0, which is used to output an ...
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### Hopping numbers

TASK print integers n, where 12 <= n <= 123456789, and all pairs of consecutive digits in n have the same positive difference between them (e.g. 2468 but not ...
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### Square pyramidal numbers

A000330 - OEIS Task Your task is simple, generate a sequence that, given index i, the value on that position is the sum of squares from ...
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### Did you hear about alphametics? [duplicate]

Task The letters spell out actual words, but if you replace each letter with a digit from 0–9, it also “spells” an arithmetic equation. The trick is to figure out which letter maps to each digit. All ...
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### Sum the means of the two integers

There are quite a few means in mathematics, such as the arithmetic mean, the geometric mean, and many others... Definitions and Task Note that these are the definitions for two positive integers*: ...
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### Exponent of complex numbers

Given two integers, which may be negative, zero, or positive, a and b (taken in any reasonable format, including inputting a ...
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### Detect the Zeroless Numbers [duplicate]

Zeroless numbers are numbers that do not contain 0 as one of their decimal digits. Given an integer K, return the Kth zeroless number. K will be non-negative if you choose 0-indexing, or positive if ...
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### Sequence of integer square roots

Let's define a sequence of integer square roots. First, a(1) = 1. Then, a(n) is the smallest positive integer not seen before such that ...
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### I am greater than you! [duplicate]

Write a function or program that given a list of non negative integers, arranges them such that they form the largest possible number. INPUT [50, 2, 1, 9] ...
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### Recursively concatenated cumulative sums of [N] with M iterations

Take two positive integers N and M and create the concatenated cumulative sums of [N], with <...
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### Make a list continuous! [duplicate]

Take an input list L containing positive integers, and insert the least amount of integers into the sequence, so that you make it a continuous one. Example: ...
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### A Euro-iginal Sequence

Given a positive integer n output the n-th number of the euro-iginal sequence. Calculating the Sequence This sequence is equal to OEIS A242491. A number is part of said sequence if the number can ...
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### Prime Factoral Roots

Inspired by digital roots, the prime factoral root of a number is the number that emerges when you take the prime factors of a number, add them together, and repeat the process on the resulting number,...
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### Narcissistic array elements

Definition Narcissistic 1 integers of an array think they are better than their neighbours, because they are strictly higher than their arithmetic mean. Neighbours are defined as follows: If the ...
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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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### 90% fail this challenge?

I guess I'm not the only one who have seen this kind of image on Facebook (and other sites). The picture above was posted 16 days ago, and has accumulated 51 k comments. Some answers: 0, 4, 8, 48, ...
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### How many Wazirs can be placed on an N×N Chessboard?

Suppose a new fairy chess piece named the Wazir is introduced to chess. Wazirs can move from a position (x, y) to:  (x+1, y)  (x, y+1)  (x-1, y)  (x, y-1) That is, they move orthogonally like the ...
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### Prime Factorial [duplicate]

For the purposes of this question, the prime factorial of a number n is the result of multiplying all prime numbers smaller than n, and then multiplying the result by n. Your Task: Write a program ...
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### Increasing, decreasing, none or all?

Take two inputs, a non-empty vector/list containing digits 1 and 2 and a string (no, you may not take ...
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### Illustrate the Least Common Multiple

Given two positive integers, A and B, illustrate their least common multiple by outputting two lines of dashes (-) with length LCM(A, B) after replacing every Ath ...
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### Generate Numpad-Friendly Numbers

Inspired by Generate Keyboard Friendly Numbers. Background Many number pads have the following layout: 789 456 123     0     We define a number's ...
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### Am I an insignificant array?

An insignificant array is an array of positive integers, where the absolute differences between consecutive elements are all smaller than or equal to 1. For example, the following array is ...
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### Pandigital Doubling

Inspired by this CMC Given a positive integer greater than 0, perform the following operation on it: If all ten single digits (1234567890) are in the number at ...
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### Is it a completely even number?

A completely even number is a positive even integer whose divisors (not including 1) are all even. Some completely even numbers are 2 (divisors: 2, 1), 4 (divisors: 4, 2, 1), 16 (divisors: 16, 8, 4, ...
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### Reverse Maths Cycles

Inspired by this In the linked challenge, we are asked to apply addition to the elements of the original and the reverse of the input array. In this challenge, we are going to make it slightly more ...
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### How many Lynch-Bell numbers are there?

Challenge Given an integer, n, as input where 36 >= n >= 2, output how many Lynch-Bell numbers there are in base ...
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### Weird grading system

Weirdo Incorporates have a weird way of grading their staffs by the number of days they were present in the office: ...
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### Implement the Fibonacci sequence… Shifted to the right [duplicate]

Background We all know the famous Fibonacci sequence, where each term is the sum of the previous two, with the first term being 0 and the second one being ...
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### Max power of 2 such that 2^m divides n. (The ruler sequence) [duplicate]

Input: A positive integer N. Challenge: Suppose you have a list of integers n = 1, 2 ... N. Output a list of integers, where each number is the maximum power of 2, m, such that 2^m divides each ...
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### Help! My calculator malfunctions!

Introduction My calculator is behaving weird. Sometimes when I type in an 8 it displays a 2. And sometimes when I type in a <...
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### Calculate the area of a regular polygon

Given an integer, n, where 3 <= n < 2^32, calculate the area of a regular n-gon with ...
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### Generate strong primes [duplicate]

In number theory, a strong prime is a prime number that is greater than the arithmetic mean of the nearest prime above and below (in other words, it's closer to the following than to the preceding ...
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### Shifting digits

Given a string representing a number and the base that number is in, shift each positional value upward, wrapping back to zero if the value cannot increase. You will never be provided invalid input, ...
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### First spiral, then diagonal

Given a positive input number n, construct a spiral of numbers from 1 to n^2, with ...
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You will be given two arrays of floating-point numbers. Your task is to pair the corresponding elements of the two arrays, and get the maximum of each pair. However, if the two corresponding elements ...
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### Playing Darts: become an amateur with the most efficient prioritizing

Introduction: I think most people will know how darts work. But since some might not, here are the rules of playing Darts in a nutshell: Amount of players: 2 Starting points: 501 Goal: Get your ...