Questions tagged [number]
A competition to solve a particular problem through the usage and manipulation of numbers.
1,169
questions
4
votes
14answers
650 views
Written Word Equation
Word equations, but not as you know it! Given a sentence which will include two numbers, numerically, and a spelt operator, in the order seen in the examples, your goal is to give the numerical answer
...
19
votes
18answers
2k views
Adaptive randomisation
Given a number \$n ≥ 2\$, a blackbox function \$f\$ that takes no arguments and returns a random integer in the range 0...n-1 inclusive, and a number \$m ≥ n\$, your challenge is to generate a random ...
10
votes
32answers
1k views
Index and return 3 characters
The challenge is simple: Read 3 letters from a system input¹ and convert them to numbers (A-1, B-2, C-3...Z-26)². Print each of those numbers in the order the ...
5
votes
3answers
378 views
Will the hydra finally die? Part II
Background
This is a follow up question to the question: Will the Hydra finally die?
As before a dangerous A Medusa have released a dangerous Hydra which is revived unless the exact number of heads it ...
19
votes
10answers
1k views
Ploughed fields via moduli
Let \$R, C\$ be positive integers and let \$0 < s \leq 1\$. Consider the \$R \times C\$ matrix \$\mathbf M\$ defined as
\begin{equation}
M(i,j) = \frac{\mathrm{mod}\,(j, i^s)}{R^s}, \quad i = 1, \...
15
votes
10answers
2k views
Project Euler 1: Multiples in constant time
The purpose of this challenge is to solve the original first Project Euler problem, but as the title suggests in constant time (with respect to the size of the interval).
Find the sum of all the ...
21
votes
12answers
2k views
Is it a Giuga number?
Giuga numbers (A007850) are composite numbers \$n\$ such that, for each prime factor \$p_i\$ of \$n\$, \$p_i \mid \left( \frac n {p_i} -1 \right)\$. That is, that for each prime factor \$p_i\$, you ...
4
votes
9answers
2k views
Will the Hydra finally die?
Background
A Medusa have released a dangerous Hydra which is revived unless the exact number of heads it have is removed. The knights can remove a certain number of heads with each type of attack, and ...
21
votes
16answers
2k views
Largest Number with No Repeating Digit Pairs
Inspired by the problem with the same name on Puzzling SE by our very own Dmitry Kamenetsky.
You are to find the largest number that only uses every digit pair once, in a given base. For example, in ...
27
votes
33answers
2k views
Mr. Binary Counterman
Mr. Binary Counterman, son of Mr. Boolean Masker & Mrs. Even Oddify, follows in his parents’ footsteps and has a peculiar way of keeping track of the digits.
When given a list of booleans, he ...
25
votes
12answers
2k views
Collatz's ice cream cone factory
The Collatz sequence
Given a positive integer \$a_1\$, the Collatz sequence with starting value \$a_1\$ is defined as
\begin{equation}
a_{n+1} =
\begin{cases}
a_n/2 & \mathrm{if}\ a_n\ \mathrm{is}\...
7
votes
10answers
585 views
A triangle of numbers
Challenge
Make a triangle of numbers like below.
How to?
Let say we get a numbers in the form of ab, for example 12. We then create a triangle like below:
Sorry ...
10
votes
13answers
678 views
'Plane' the numbers in any base!
Inspired by this Numberphile video.
What is planing?
In order to 'plane' a sequence of digits, you need to:
Identify the lengths of the 'runs' (adjacently repeated digits) in the sequence. Non-...
11
votes
7answers
739 views
Prime Factorization - but on the exponents too
Though there is a prime factorization challenge and it's here, this, I feel, will be a bit more interesting than that one.
To understand this, let's have an example; I will use 5,184 for this. \$5184 =...
2
votes
3answers
518 views
Programming Less-Than, Greater-Than and Equal-To functions using Restricted Source [closed]
I'm currently working with a branchless language which does not have native Less-Than, Greater-Than or Equal-To functions. I do however have min, ...
7
votes
14answers
582 views
Calculate \$ \lfloor n \log_2(n) \rfloor \$, exactly
Given an integer \$ n \ge 2 \$, you need to calculate \$ \lfloor n \log_2(n) \rfloor \$, assuming all integers in your language are unbounded.
However, you may not ignore floating-point errors - for ...
17
votes
9answers
1k views
Dimensional Chess positions
Task
Any one of these two:
Determine if a given position (an ordered non-empty collection of integers in the range ‒8 to 8, or ‒7 to 7 if you want) is a valid Dimensional Chess position.
List all the ...
14
votes
15answers
1k views
Convert version string to pack_format
When making a Minecraft data/resource pack, you need to include a pack.mcmeta file, which specifies information about it. ...
11
votes
5answers
430 views
Set the sum and product
Given two positive reals \$a\$ and \$b\$, output some positive reals \$r_i\$, such that \$\sum r_i=a\$ and \$\prod\left(r_i+1\right)=b\$. You can assume that it's possible. You can also assume that ...
16
votes
3answers
555 views
Compute the uncomputable ... sort of
Implement a function \$f\$ (as a function or complete program), such that
\$
\displaystyle\lim_{n\rightarrow \infty} f(n)
\$
converges to a number which is not a computable number.
Answers will be ...
5
votes
12answers
909 views
Base-ically Guard
Base: part 1
This is part 2, Strongly suggest you go try out the first one if you haven't tried it.
Story
As one of the solvers, You've managed to get to the door of the base heaven. In front of the ...
22
votes
33answers
2k views
Apply at indices
Given:
a blackbox function \$f : \mathbb N \to \mathbb N\$,
a list of positive integers \$L\$, and
a list of indices \$I\$,
apply \$f(x)\$ to the elements of \$L\$ at the indices specified in \$I\$.
...
19
votes
9answers
2k views
What's my lucky factor?
Lucky numbers (A000959) are numbers generated by applying the following sieve:
Begin with the list of natural numbers:
...
10
votes
21answers
3k views
Exciting Mario Kart Grand Prix - Minimize the point difference!
Introduction
When playing Mario Kart the other day, an interesting question popped up when a Grand Prix with my 2 roommates, 9 AI drivers and myself seemed to be fairly close and therefore exciting ...
8
votes
17answers
1k views
Base-ically god
Story
The god of base is opening heaven’s gate for mortals to join the base party. You, as one of the believers, want to follow their steps to ascend to heaven.
But not everyone can get in.
The god ...
14
votes
19answers
2k views
Do I need a win streak?
You have played \$N\$ matches in some game where each match can only result in one of the two outcomes: win or loss. Currently, you have \$W\$ wins. You want to have a win percentage of \$P\$ or more, ...
19
votes
6answers
1k views
You are kinda Replacable to Me
You are provided with a non-empty array \$A\$ of integers, all greater than 0. But what good is an array if the elements do not sum up to the number \$N\$ (also provided as input)...
So to change that,...
1
vote
4answers
210 views
A problem of rarity [closed]
Given a positive input \$n > 0\$, output the amout of two types based on their rarity. The two types are called \$A\$ and \$B\$, we know the followings:
\$n\$ is a limited input and the maximum is ...
21
votes
20answers
2k views
Code the Levine sequence
Introduction
Note that I learned it from a Numberphile Video, where Neil Sloane explains it better. I recommend you to watch his Video. But for a quick Introduction:
The Levine Sequence is made from ...
25
votes
31answers
4k views
Count all possible Tweets
Challenge
This challenge is pretty simple: Output the total number of possible Tweets. Given the fact that \$1114112\$ Unicode characters exist, and Tweets can be up to \$280\$ characters long, we ...
24
votes
10answers
1k views
Unique half rainbows
If we take a positive integer \$n\$ and write out its factors. Someone can determine \$n\$ just from this list alone. In fact it is trivial to do this since the number is its own largest factor.
...
18
votes
16answers
2k views
Self-Replicating Numbers
Background
For the purpose of this challenge, all numbers and their string representations are assumed to be in decimal (base 10). I tried to find proper terminology for this challenge, but I do not ...
15
votes
30answers
925 views
Largest power of 2 that divides \$n\$
Related, related
Introduction
The ruler sequence is the sequence of the largest possible numbers \$a_n\$ such that \$2^{a_n}\mid n\$. It is so-called because its pin plot looks similar to a ruler's ...
12
votes
17answers
966 views
Liars and Guessers
Github
You have probably played, and may even have written a program to play, a simple number guessing game. If so, this probably looks familiar:
...
-3
votes
8answers
952 views
Let's rise higher [closed]
Challenge
The main objective of the challenge is pretty simple, this is an answer chaining contest, where you have to serially print numbers from 1. That means User 1's answer will print ...
29
votes
24answers
2k views
First sequence with no square differences
Consider the sequence \$(a_n)\$ defined in the following way.
\$a_0=0\$
For all \$n=1, 2, 3, \dots\$, define \$a_n\$ to be the smallest positive integer such that \$a_n-a_i\$ is not a square number, ...
23
votes
34answers
2k views
Remove excessive occurrences
Given an array \$A\$ of positive integers between \$1\$ and \$9\$ inclusive and a positive integer \$n\$, remove all integers in \$A\$ which appear more than \$n\$ times.
For example:
...
39
votes
105answers
10k views
Print 0 to 100 without 1-9 characters
Print 0 to 100 without using characters 1,2,3,4,5,6,7,8,9 in your code.
Seperator of numbers can be comma, whitespace or newline.
Shortest code wins.
11
votes
6answers
770 views
Golf this Thumb-2 Constant!
One thing that is constantly frustrating when golfing ARM Thumb-2 code is generating constants.
Since Thumb only has 16-bit and 32-bit instructions, it is impossible to encode every immediate 32-bit ...
46
votes
24answers
4k views
15
votes
8answers
732 views
Close(st) Binary Boxes
Challenge:
Given a list of non-negative integers, determine by how much you should increase each item to create the closest binary box with the resulting integer-list.
What is a binary box?
A binary ...
13
votes
21answers
1k views
Get the length of a Sumac Sequence
Heavily based on this closed challenge.
Codidact post, Sandbox
Description
A Sumac sequence starts with two non-zero integers \$t_1\$ and \$t_2.\$
The next term, \$t_3 = t_1 - t_2\$
More generally, \$...
15
votes
14answers
1k views
Split a number in every way possible way within a threshold
Task
Given a positive integer number and a threshold, split into every possible way without generating any numbers above the threshold.
Examples
Input: 15008
Threshold: 400
Valid Output:
...
4
votes
5answers
224 views
Strobogrammatic Numbers [duplicate]
Strobogrammatic Numbers
Definition
A number which is rotationally symmetrical, i.e., it'll appear the same when rotated by 180 deg in the plane of your screen. The following figure illustrates it ...
21
votes
25answers
1k views
Possible binaries sum
This challenge is inspired by the AoC 2020, Day 14 - Part II, created by Eric Wastl and his team, which asks to output the possible binary values from a bitmask.
Let's say we've a bitmask like ...
23
votes
3answers
688 views
Towering Cistercian representation
SE Sandbox Link, Codidact Sandbox Link
Inspired by this video.
Given a positive integer, draw its Cistercian representation as ascii art.
The Challenge
Cistercian numerals are a decimal-based number ...
26
votes
17answers
3k views
Convert negadecimal to decimal (and back)
Negadecimal, also known as base -10, is a non-standard positional numeral system.
Take the number \$1337_{10}\$. In decimal, this has the value one thousand three hundred thirty seven, and can be ...
10
votes
7answers
2k views
Fastest square root of an arbitrary size
We do seem to have a fastest square root challenge, but it's very restrictive. In this challenge, your program (or function) will be given an arbitrarily sized nonnegative integer, which is the square ...
19
votes
32answers
2k views
Make a minimal and maximal 2-digit number from digits of two 3-digit numbers
Let's solve this user's homework; I think it's an interesting exercise!
Input
Two 3-digit natural numbers.
Outputs
Two 2-digit numbers. In each of the output numbers, one digit is taken from one input ...
11
votes
14answers
870 views
Prefix divisibility
Inspiration
Given a positive integer \$1 \le n \le 9\$, output all positive \$n\$-digit integers \$i\$ for which the following is true:
Each digit from \$1\$ to \$n\$ appears exactly once in \$i\$. ...