# Questions tagged [number]

A competition to solve a particular problem through the usage and manipulation of numbers.

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### Find all Belphegor primes

A Belphegor number is a number of the form $(10^{n+3}+666)*10^{n+1}+1$ (1{n zeroes}666{n zeroes}1) where $n$ is an non-negative integer. A Belphegor prime is a ...
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### Closest to a square

The task Given a positive integer c, output two integers a and b where ...
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### Build the smallest number

Given a non-empty list of digits 0 though 9, output the smallest number that can be produced by an expression formed by reordering these digits and introducing exponentiation signs ...
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### How to find the original value based on modulus/reminder and some other information [closed]

This might be a very basic question in terms of math, x % constant = x_modulus (x + some_number) % constant = y_modulus Given the value of ...
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### Calculate The Digit Sum

Your task is to get two numbers, and output the digit sum of them. We'll define digit sum as the following: take the decimal (base 10) digits of each of them, and pad with 0s the shortest number (e.g....
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### Binary Reduce a List By Addition With a Right Bias

Given a list of 2 or more strictly positive integers, sum the first and last half of the list, with the middle element being counted only in the right half if the list has an odd number of elements ...
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### The "skip-pure" numbers

The skip-pure numbers are defined with this rule: ...
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### Base-phi converter time!

The Golden Ratio Bureau is obsessed with this new thing they call base-phi. You see it and decide to code-golf, as is your natural instinct. To be specific, base-phi is a number system like base 10, ...
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### Evaluate Conway chained arrow notation

Background Conway chained arrow notation is a notation to express very large numbers. It consists of zero or more positive integers separated by right arrows, e.g. $2 \to 3 \to 4 \to 5 \to 6$. ...
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### Multiple, Lit Plume, Mute Pill and so on

We say two positive integers are anagrams of each other if the digits in one of them (in decimal representation) can be rearranged to form the other. Leading zeros don't count. For example, 110020222 ...
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### Donation arms race

The barfoos, a hypothetical alien species, go about charity in an interesting way. Every morning, barfoo Specialists come up with an ordered list of causes to donate to, and for each cause they ...
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### Missile-mounted cameras

You are employed as Administrator in charge of Road Maintenance and Planning. The intelligence division of the Agency for Road Maintenance and Planning has come up with a brilliant and not at all ...
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A recent SO question asks for a convenient one-liner to generate a list of numbers and their negative counterparts in Python. Given two integers $1≤a≤b$, generate all the integers $x$ such that $... • 29.9k 24 votes 11 answers 2k views ### Find a Similar Number We consider two integers to be similar if, when written in decimal, have the same length, and if we compare characters in any two positions for both decimal strings, the comparison results (less, ... • 1,150 19 votes 22 answers 4k views ### Convert to and from Base 94 The challenge Make 2 programs which convert decimal to and from base 94, or a bidirectional program. Base 94? Base 94 is like any other base, but instead of 0 to 9 and letters, it uses ASCII ... • 2,693 21 votes 27 answers 3k views ### A bit of a digital XOR Here are the first 100 numbers of a sequence: ... • 123k 3 votes 5 answers 202 views ### Find the binary period [duplicate] We know that not all fractions have a terminating binary representation. However every fraction can be written as a leading portion followed by a repeating portion. For example$1/3$starts with$...
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My robot for generating Mad Libs-style sequence challenges has gone rogue! To defeat it, I need you to write code that can solve all the challenges it can crank out. Your input is three selections ...
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### Any lips images

Introduction The $n$-ellipse is a generalization of the ellipse with possibly more than two foci. Specifically, given $n$ points on the plane, called foci, the $n$-ellipse is the set of points ...
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### Counting Distinct Real Roots of Low-Degree Polynomials

Challenge: I want to know about the real roots of polynomials. As a pure mathematician, I care about the existence of such roots, rather than their numeric values. The challenge is to write the ...
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### Find self-locating strings in a number

Based on this Numberphile video A self-locating string is a number (or set of numbers) in a decimal expansion which corresponds to its location, from the start of the decimal. For example, take the ...
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### How many unique one sided polyominos

Context From Wikipedia: A polyomino is a plane geometric figure formed by joining one or more equal squares edge to edge. one-sided polyominoes are distinct when none is a translation or rotation of ...
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### Is it a doubling sequence?

A doubling sequence is an array of numbers where each subsequent number is at least twice the previous number. Given an ordered list of numbers, determine if the numbers in the list ($n_{x}$) have ...
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### Convert a string of digits from words to an integer

Convert a string containing digits as words into an integer, ignoring leading zeros. Examples "four two" -> 42. ...
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### Given a sequence of numbers, print out all possible sets such that the sum is less than a number

The problem has 3 inputs. L: a list of all numbers size: the size each set can be max: the max sum amongst each set The challenge is as follows: Given L, size and max, construct as many sets from ...
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