# Questions tagged [math]

The challenge involves mathematics in some central way. Also consider using more specific tags, listed in the tag wiki info.

608 questions
Filter by
Sorted by
Tagged with
3k views

### Dennis numbers 2.0

PPCG user and elected mod, @Dennis just became the second ever user to earn over 100k rep! This is a totally original idea, that I did not get from anybody else, but let's make a challenge based off ...
• 58.9k
3k views

### 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 $\text{lcm}$$(A, B)$ ...
• 89.3k
3k views

### Divisor skyline

For any positive integer $k$, let $d(k)$ denote the number of divisors of $k$. For example, $d(6)$ is $4$, because $6$ has $4$ divisors (namely $1, 2, 3, 6$). Given a positive integer \...
• 104k
6k views

### Universal Spooky Meme Translator

Introduction Turns out, aliens love memes just as much as we do. Every alien race we've encountered so far has their own version of 2spooky4me (see the following ...
• 553
8k views

### Print a bunch of uninteresting numbers!

An uninteresting number (which I totally didn't make up only for this challenge) is created like this: Take a positive integer N Create a new number O by adding the digits of N at the end of N ...
• 669
13k views

### Fibonacci reversed!

Introduction We all know and love our Fibonacci sequence and have seen a myriad of challenge on it here already. However, we're still lacking a very simple case which this answer is going to provide: ...
• 3,383
5k views

### Infinitely many ℕ

Background: A sequence of infinite naturals is a sequence that contains every natural number infinitely many times. To clarify, every number must be printed multiple times! The Challenge: Output a ...
• 523
9k views

### Is this a triangle?

Task Write a function/program that, given three positive integers a, b and c, prints a ...
• 14k
3k views

Disclaimer: This does not do any justice on the rich topic of elliptic curves. It is simplified a lot. As elliptic curves recently got a lot of media attention in the context of encryption, I wanted ...
• 43.7k
3k views

### 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, ...
• 2,284
3k views

### Make the largest infinity that you can!

The ordinal number system is a system with infinite numbers. A lot of infinite numbers. So many infinite numbers that it literally does not have an infinity to represent its own infiniteness. The ...
• 7,207
6k views

### Is this number a repdigit?

Challenge A repdigit is a non-negative integer whose digits are all equal. Create a function or complete program that takes a single integer as input and outputs a truthy value if the input number is ...
• 1,495
3k views

### Tribute to John Conway: Collatz in FRACTRAN

John Horton Conway was a brilliant mathematician. Among his contributions were three Turing-complete esolangs: Game of Life (esolangs wiki), FRACTRAN (esolangs wiki), and Collatz function (esolangs ...
• 73.8k
2k views

### One-zero dividend

Challenge description For every positive integer n there exists a number having the form of 111...10...000 that is divisible by ...
• 5,592
2k views

### Superior Passtimes

Sometimes, when I'm really bored I like to take the sum of an array of non-negative integers. I only take the sum of arrays of lengths that are powers of two. Unfortunately I often make mistakes. ...
• 841
4k views

### Circumference of an ellipse

Challenge Unlike the circumference of a circle (which is as simple as $2\pi r$), the circumference of an ellipse is hard. Given the semi-major axis $a$ and semi-minor axis $b$ of an ellipse (see ...
• 73.8k
2k views

### Output the nth rational number according to the Stern-Brocot sequence

The Stern-Brocot sequence is a Fibonnaci-like sequence which can be constructed as follows: Initialise the sequence with s(1) = s(2) = 1 Set counter ...
• 6,144
2k views

### Return the integers with square digit-sums

Introduction and Credit We all know and love our awesome rules to test whether a number is divisble by 11 or 3, which is just some clever sum over the digits of the number. Now this challenge takes ...
• 3,383
3k views

### Simplify a square root

Given a positive integer n, simplify the square root √n into the form a√b by extracting all ...
• 144k
3k views

### Subtract the next numbers

Description Subtract the next P numbers from a N number. The next number of N is N + 1. Look at the examples to get what I mean. Examples: ...
• 1,137
2k views

### Expand Exponentiation

Given two integers greater than one, A and B, output four mathematical expressions in this order: The plain expression A^B (A to the power B). e.g. if A = 2 and B = 3, ...
• 89.3k
5k views

### Calculate the permanent as quickly as possible

The challenge is to write the fastest code possible for computing the permanent of a matrix. The permanent of an n-by-n matrix ...
3k views

### Sum square difference

The sum of the squares of the first ten natural numbers is, $1^2 + 2^2 + \dots + 10^2 = 385$ The square of the sum of the first ten natural numbers is, $(1 + 2 + ... + 10)^2 = 55^2 = 3025$ ...
900 views

### Hilbertify an image

I like the Hilbert Curve. Your task for this challenge is to take an image (strictly a square image where all the sides are a power of two pixels wide) and unravel it line by line in a zig-zagging ...
• 96.6k
6k views

### Adding without using a + or - sign [closed]

There have been many "Do __ without __" challenges before, but I hope that this is one of the most challenging. The Challenge You are to write a program that takes two natural numbers (whole numbers ...
• 29k
4k views

### Simple integer operation calculator

Implement a simple integer operation scriptable calculator. Concept The accumulator starts at 0 and has operations performed on it. At the end of the program output the value of the accumulator. ...
• 6,332
3k views

### Calculate A190810

Your task is pretty simple, calculate the n-th element of A190810. Elements of A190810 are calculated according to these rules: The first element is 1 The sequence is increasing If ...
• 4,817
2k views

### Find prime gaps

A prime gap is the difference between two consecutive primes. More specifically, if p and q are primes with p <q and p+1, p+2, ..., _q_−1 are not primes, the primes p and q define a gap of n = q_−...
• 104k
4k views

### Approximation of e

We all know that the Euler's number, denoted by $e$, to the power of some variable $x$, can be approximated by using the Maclaurin Series expansion: e^x=\sum_{k=0}^{\infty}{\frac{x^k}{k!}}=1+x+\...
• 913
5k views

### Last non-zero digit of n!

Given an integer 1 ≤ N ≤ 1,000,000 as input, output the last non-zero digit of N!, where ! is the factorial (the product of all numbers from 1 to N, inclusive). This is OEIS sequence A008904. Your ...
• 4,579
3k views

### Modular multiplicative inverse

Your task is to given two integer numbers, a and b calculate the modular multiplicative inverse of a modulo b, if it exists. ...
• 3,221
7k views

### Convert infix expressions to postfix notation

When I saw the title of this closed question, I thought it looked like an interesting code golf challenge. So let me present it as such: Challenge: Write a program, expression or subroutine which, ...
• 20.7k
3k views

### Analog is Obtuse!

An analog clock has 2 hands*: Hour and minute. These hands circle the clock's face as time goes by. Each full rotation of the minute hand results in 1/12th of a rotation of the hour hand. 2 full ...
• 11.6k
4k views

### Implement the hyperfactorial

The objective Given the non-negative integer $n$, output the value of the hyperfactorial $H(n)$. You don't have to worry about outputs exceeding your language's integer limit. Background The ...
• 359
2k views

### Implement Ash's float division

Ash has a bit of an interesting float division algorithm. It's designed to never return NaN, and things like signed zero and infinity need to be handled. How it ...
• 18.6k
9k views

### Give the smallest number that has N divisors

Your function takes a natural number and returns the smallest natural number that has exactly that amount of divisors, including itself. Examples: ...
• 2,463
1k views

### Three-pointer! But what kind?

From http://en.wikipedia.org/wiki/Triangle: Write a program that takes three 2d coordinate tuples (Cartesian), and classifies what shape these three points describe. In almost all cases these points ...
• 71.8k
2k views

### Get the decimal!

Task: Your task is, when given three inputs: a numerator n a denominator d another integer, ...
• 6,982
1k views

### Calculate Power Series Coefficients

Given a polynomial $p(x)$ with integral coefficients and a constant term of $p(0) = \pm 1$, and a non-negative integer $N$, return the $N$-th coefficient of the power series (sometimes called &...
• 43.7k
2k views

### Delicate primes

Inspired by Find the largest fragile prime. By removing at least 1 digit from a positive integer, we can get a different non-negative integer. Note that this is different to the ...
• 49.5k
1k views

### Interpret Interval Notation

Interval notation is a way to write complicated range bounds more conveniently and concisely than writing an inequality. The challenge, should you choose to accept it, is to write a program or ...
• 2,435
787 views

### Product over exclusive and inclusive ranges

Inspired by this question by @CᴏɴᴏʀO'Bʀɪᴇɴ. Taken from the question: Your task is simple: given two integers a and b, output ∏[a,b]; that is, the product of the range between a and b. You may ...
1k views

### Reverse Engineer Polling Statistics

Introduction Given a set of percentages of choices in a poll, calculate the minimum number of voters there must be in the poll to generate those statistics. Example: What is your favorite pet? Dog: ...
• 6,073
2k views

### Diamond Puzzles!

Explanation: Last year in math class, on homework we would occasionally get these extremely simple, although equally annoying questions called diamond puzzles. These were basically questions where we ...
• 481
3k views

### Sum of two squares

Given a nonnegative integer $n$, determine whether $n$ can be expressed as the sum of two square numbers, that is $\exists a,b\in\mathbb Z$ such that $n=a^2+b^2$. ...
• 4,964
3k views

### Prove me wrong!

Introduction Your mission in life is simple: Prove people wrong on the internet! To do this you usually carefully analyze their statements and point out the contradiction in them. It's time to ...
• 3,383
2k views

### The Euclidean Algorithm (for finding the greatest common divisor)

The Challenge Write a program or function that takes two input integers, i and j, and outputs their greatest common divisor; ...
• 6,660
2k views

### Gamma Function Golf

Given a real number t in (-10^9,13) (not including -10^9 or ...
3k views

### Parallel resistance in electric circuits

Introduction: Two resistors, R1 and R2, in parallel (denoted R1 || R2) have a combined ...
• 46.2k
Landau's function $g(n)$ (OEIS A000793) gives the maximum order of an element of the symmetric group $S_n$. Here, the order of a permutation $\pi$ is the smallest positive integer $k$ such ...