Questions tagged [arithmetic]
Challenges related to elementary arithmetic.
10
votes
16answers
129 views
Multiplicative persistence
Multiplicative Persistence
Multiply all the digits in a number
Repeat until you have a single digit left
As explained by Numberphile:
Numberphile "What's special about 277777788888899?"
Numberphile ...
33
votes
5answers
8k views
Historical difference between `/` and `÷` in mathematical expressions
Introduction:
Inspired by a discussion that is already going on for many years
regarding the expression \$6÷2(1+2)\$.
With the expression \$6÷2(1+2)\$, mathematicians will quickly see that ...
17
votes
14answers
1k views
Spot all (anti)diagonals with duplicated values
Challenge:
Given a matrix input, determine the amount of diagonals and anti-diagonals with duplicated numbers.
So if we have a matrix like this:
...
1
vote
2answers
192 views
Work out \$x^y\$ using only addition and subtraction [duplicate]
The challenge is to implement a function or program that takes two numbers, \$x\$ and \$y\$ and return the result of \$x^y\$.
The program cannot use any other mathematical operation other than \$+\$ ...
2
votes
3answers
121 views
All the digisibles [duplicate]
A natural number (written in the decimal base) is qualified as digisible if and only if it fulfills the following 3 conditions:
none of its digits is zero,
all the digits that compose it are ...
14
votes
25answers
1k views
Standardize the Samples (Compute the z-Score)
Given a list of floating point numbers, standardize it.
Details
A list \$x_1,x_2,\ldots,x_n\$ is standardized if the mean of all values is 0, and the standard deviation is 1. One way to compute this ...
14
votes
19answers
3k views
How much candy can you eat?
Credit to Geobits in TNB for the idea
A post without sufficient detail recently posited an interesting game:
2 children sit in front of an array of candy. Each piece of candy is numbered 1 to ...
-3
votes
6answers
143 views
Measuring Mountains [duplicate]
Sum-It is a language I created (quite late) for the Language Design Contest in TNB, for which the theme was "Range". Naturally I interpreted this as "Mountain Range" and created a language about ...
19
votes
38answers
2k views
Given an input, print all exponents where the base and power sum to the input
So this is my first challenge on this site.
The challenge is to take in an input integer \$n\$, which will be positive, and print, in ascending order (\$1\$ to \$n\$, including n), the output of \$i^{...
19
votes
13answers
1k views
Dirichlet Convolution
The Dirichlet convolution is a special kind of convolution that appears as a very useful tool in number theory. It operates on the set of arithmetic functions.
Challenge
Given two arithmetic ...
19
votes
27answers
3k views
Strange Addition
Challenge
Calculate the strange sum of two natural numbers (also known as lunar addition):
Given A=... a2 a1 a0 and ...
17
votes
19answers
2k views
The Written Digits Sequence
Here's a reasonably trivial sequence which is not in the Online Encyclopedia of Integer Sequences.
Start with an empty sequence then define each term as the number of characters required to write out,...
2
votes
13answers
452 views
Validate a barcode [duplicate]
A barcode of EAN-13 symbology consists of 13 digits (0-9). The last digit of this barcode is its check digit. It is calculated by the following means (the barcode ...
10
votes
7answers
638 views
Whose neighbours are hostile?
Introduction
For the purposes of this challenge, we will define the neighbours of an element \$E\$ in a square matrix \$A\$ (such that \$E=A_{i,j}\$) as all the entries of \$A\$ that are immediately ...
7
votes
17answers
556 views
Extract and Divide
Challenge
For a given positive integer \$n\$:
Repeat the following until \$n < 10\$ (until \$n\$ contains one digit).
Extract the last digit.
If the extracted digit is even (including 0) multiply ...
14
votes
15answers
1k views
Missing numbers in arithmetic sum
Challenge
Giving a valid arithmetic sum with some missing numbers, output the full expression.
Example:
...
30
votes
18answers
2k views
Custom Number Base Converter
The powers that be want to be able to quickly convert any number they have into their own number base using any format they would like.
Input
Your program must accept 3 parameters.
Number: The ...
18
votes
21answers
2k views
Divide the work
There is a job which can be decomposed into x equally-sized smaller tasks. You have a team of size y <= x, where every member ...
17
votes
34answers
955 views
Calculate power series result [duplicate]
Related: Calculate Power Series Coefficients
Given a positive integer \$X\$ and a max exponent (Also a positive integer too) \$N\$ calculate the result of a power series. Example:
$$X^0+X^1+X^2+\...
21
votes
2answers
413 views
Subset Sum Orderings
A set of n positive numbers has 2^n subsets. We'll call a set "nice" if none of those subsets have the same sum. ...
21
votes
2answers
574 views
Double a number's continued fraction
Your task is, given x, output 2*x. Easy right!? But there's a catch: x will be given as a (...
16
votes
31answers
1k views
Recover the power from the prime power
It seems that many people would like to have this, so it's now a sequel to this challenge!
Definition: a prime power is a natural number that can be expressed in the form pn where p is a prime and n ...
13
votes
32answers
2k views
Recover the prime from the prime power
Definition: a prime power is a natural number that can be expressed in the form pn where p is a prime and n is a natural number.
Task: Given a prime power pn > 1, return the prime p.
Testcases:
<...
4
votes
1answer
320 views
Pair and sort from two integer lists
You are given two arbitrary integer lists, e.g. [-10, 99, -6, 43], [100, 32, 44]. You are to pick one integer from each list and ...
7
votes
4answers
859 views
Insulate the Window Glass and Foil of your house
Introduction:
The best options for the glass of your house will:
1. Let through as little heat as possible in both directions (insulation-value Ug).
(2. Let ...
9
votes
2answers
440 views
Interpreted arithmetic
A little known fact is that if you turn on enough language extensions (ghc) Haskell becomes a dynamically typed interpreted language! For example the following program implements addition.
...
3
votes
0answers
161 views
Make Three from One [duplicate]
Given a single digit integer and a three digit integer, output a mathematical formula that uses only the single digit and a given list of operators to equal the three digit integer.
Input: A one ...
11
votes
1answer
362 views
Not just a four fours puzzle
In this variant of the Four fours puzzle your should use up to x x's (and no other number) and a defined set of operations to ...
-1
votes
1answer
194 views
Find the longest uninterrupted arc in N dimensions
See similar question for 2D case: Find the longest uninterrupted arc
The challenge here is to find the longest uninterruped great circle arc around a unit hypersphere in N dimensions, with a random ...
5
votes
3answers
335 views
Find the longest uninterrupted arc
The challenge here is to find the longest uninterruped arc around a unit circle with a random amount of points distributed in random positions around it.
Here is a diagram to assist my explanation:
...
20
votes
5answers
1k views
Golfing out the haters
The setup:
A social network reports the number of votes a post has in two ways: the number of net upvotes (total upvotes - total downvotes), and the % of votes that were upvotes, rounded to the ...
7
votes
2answers
191 views
Minimal Triangles
Make an upside down triangle of positive integers. Every number in the triangle must be distinct. Each number is the summation of its two parents (similar to how Pascal's triangle is constructed, but ...
5
votes
27answers
1k views
Simple Factorial Challenge [duplicate]
In light of today's date...
A factorial of a number n, is the product of all the numbers from 1 to n inclusive.
The Challenge
Given an integer n where 0 <= n <= 420, find the sum of the ...
15
votes
12answers
766 views
Number of surjections
Task
Given 2 positive integers n and k, where n > k, output the number of surjections ...
12
votes
50answers
3k views
Integer logarithms
Given integers N , P > 1 , find the largest integer M such that P ^ M ≤ N.
I/O:
Input ...
13
votes
13answers
1k views
32
votes
24answers
4k views
Sum of five cubes
Given an integer, output five perfect cubes whose sum is that integer. Note that cubes can be positive, negative, or zero. For example,
...
25
votes
30answers
4k views
Zero-sum counting
Write a program or function that given n ≥ 1 returns the number of solutions to ±1 ± 2 ± 3 ± ... ± n = 0.
For n = 6 there are no solutions, so the answer is 0. For n = 4 there are ...
14
votes
30answers
3k views
Two steps forward and one step back
Let's say I'm ten steps away from my destination. I walk there following the old saying, "Two steps forward and one step back". I take two steps forward, one back, until I'm standing exactly on my ...
22
votes
24answers
2k views
Ten-pin bowling score - World Bowling edition
World Bowling scoring
Many people have gone to their local bowling center to play a few games of bowling, and many people continue to struggle to calculate their scores. World Bowling has introduced ...
26
votes
3answers
1k views
Golf A Free Lunch
Find a maximally profitable sequence of exchanges given an exchange rate table.
As an example consider the currencies Ariary (your home currency), Baht, Cedi, and Denar where the rate from one to ...
19
votes
26answers
1k views
Given a number, print out its “collective sum”
Given a number as input, print out its collective sum
What is a collective sum?
Consider the number 13214, the input
Looping through each of the digits starting ...
-6
votes
45answers
873 views
Quartic Summation
Guidelines
Task
Given two non-negative integers, find the sum of both numbers... to the power of 4.
Examples
2, 3 -> 97 (2^4 + 3^4 = 97)
...
26
votes
22answers
2k views
Diluted Integer Sums
A positive integer can be diluted by inserting a 0 between two bits in its binary expansion. This means that an n-bit number has ...
28
votes
8answers
2k views
Find number of ones to get a number using + and *
Introduction
Your goal is to find the least number of ones you need to add or multiply together to get the input value, this is A005245.
Input
One positive integer N.
Output
The smallest number ...
18
votes
12answers
2k views
Olympic Rings Sequence
Challenge:
Given an index integer n, either output the n'th item in this sequence, or output the sequence up to and including ...
6
votes
3answers
285 views
Accumulate some L.s.d
Prior to the decimalisation of Sterling in February 1971, a pound (£ - from Roman libra) comprised 20 shillings (s - solidus), each of 12 pennies (d - denarius). Additionally, until 1960, each penny ...
24
votes
62answers
3k views
The Non-Zero Digital Product Challenge
Originally the Multiplicative digital root
Challenge
Basically do what the title says
Method
Given a positive integer 1 <= N <= 100000000 through one of our standard input methods, multiply ...
12
votes
10answers
1k views
Create an N-Dimensional Simplex (Tetrahedron)
The Simplest N-Dimensional shape one can create for any dimension is a Simplex, and this is a set of N+1 points that are all equal distance away from eachother.
For 2 dimensions, this is an ...
12
votes
18answers
943 views
Encrypted In Numbers!
The Problem:
Two enemy secret agents have devised a wonderful (for you) method of communication!
Here’s how the encryption process works:
1) Take the ascii equivalents of each letter. (No spaces, ...
