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Questions tagged [number]

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

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60 votes
273 answers
17k views

Print numbers from 1 to 10

This might be a very simple challenge, but I am surprised it hasn't been done on code-golf yet: Print all Integers from 1 to 10 inclusive in ascending order to standard output. Your output format ...
84 votes
193 answers
10k views

Output the sign

Given a number N, output the sign of N: If N is positive, output 1 If N is negative, output -1 If N is 0, output 0 N will be an integer within the representable range of integers in your chosen ...
144 votes
95 answers
32k views

Largest Number Printable

Your goal is to write a program that prints a number. The bigger the number, the more points you'll get. But be careful! Code length is both limited and heavily weighted in the scoring function. Your ...
56 votes
11 answers
12k views

Golf a number bigger than TREE(3)

The function TREE(k) gives the length of the longest sequence of trees T1, T2, ... where each vertex is labelled with one of k colours, the tree Ti has at most i vertices, and no tree is a minor of ...
27 votes
6 answers
6k views

Golf a number bigger than Loader's number

As a follow up to Shortest terminating program whose output size exceeds Graham's number and Golf a number bigger than TREE(3), I present a new challenge. Loader's number is a very large number, ...
43 votes
92 answers
5k views

Output the missing integer

You will be given a string. It will contain 9 unique integers from 0-9. You must return the missing integer. The string will look like this: ...
23 votes
29 answers
2k views

Borders of a Rectangular Matrix

Although it's done a few times as sub-challenge of a larger challenge, and we also have a challenge to remove the borders of a square matrix, I couldn't find a challenge to output the borders of a ...
27 votes
48 answers
8k views

Distance between two points in n-dimensional space

Here is another simple one: The Challenge Given two points in an n-dimensional space, output the distance between them, also called the Euclidean distance. The coordinates will be rational numbers; ...
24 votes
30 answers
3k views

A bit of a digital XOR

Here are the first 100 numbers of a sequence: ...
236 votes
369 answers
66k views

Is this number a prime?

Believe it or not, we do not yet have a code golf challenge for a simple primality test. While it may not be the most interesting challenge, particularly for "usual" languages, it can be nontrivial in ...
17 votes
21 answers
2k views

Divmod continuously until the remainder is 1 or 0, then get the remainder

The task is simple, divide, get the quotient and the remainder, and if the remainder isn't 1 or 0, do the same thing (quotient divmod remainder) until the remainder is 1 or 0, then get the remainder. ...
149 votes
336 answers
44k views

Fibonacci function or sequence

The Fibonacci sequence is a sequence of numbers, where every number in the sequence is the sum of the two numbers preceding it. The first two numbers in the sequence are both 1. Here are the first ...
50 votes
40 answers
3k views

Last odd digit of power of 2

Task Given \$n\$, output position of the last odd digit in the decimal representation of \$2^n\$ (counting from the end). Rules There are no odd digits for \$n=1,2,3,6,11\$ \$(2, 4, 8, 64, 2048)\$ - ...
11 votes
23 answers
895 views

Construct a uInt from an array of bits

Task is simple! Take an array of binary values (can be boolean, 0/1, etc.) and use those bits to construct an n-th bit long unsigned integer (return type does not need to be an unsigned integer, just ...
23 votes
32 answers
1k views

Find the indices of values in one list in another

You must take two lists of positive integers as input, let's call these n and m. You may assume that: All integers in n are part of m All integers in m are unique The lists are non-empty Challenge:...
6 votes
4 answers
1k views

Hoop, Hoop, Hoop, Hoop, Eye-Eye-Eye-Eye

The Horrible Histories song "Learn Your Hieroglyphics" mentions a fanmade number system. Numbers are written as a sum of 10's ("hoops") and 1's ("eyes"), for example 99 ...
36 votes
46 answers
5k views

Half, Half Half, and, Half

Consider the following number sequence: \$ 0, \frac{1}{2}, \frac{1}{4}, \frac{3}{4}, \frac{1}{8}, \frac{3}{8}, \frac{5}{8}, \frac{7}{8}, \frac{1}{16}, \frac{3}{16}, \frac{5}{16}, \frac{7}{16}, \...
40 votes
41 answers
5k views

Is there a bump?

Given a list of positive integers determine if there is an element that is either greater than its two neighbors or less than its two neighbors (a "bump"). To be clear a bump can never be the first ...
27 votes
25 answers
8k views

1, 2, 4, 8, 16, ... 33?

Challenge Write a function/program that outputs either the n'th element, or the first n elements, in the well known number ...
16 votes
19 answers
1k views

Infer pluses and minuses

The problem Consider an equation such as      "3 ± 2 ± 4 ± 1 = 4"      and determine if there exists a sequence of pluses and minuses that makes it arithmetically correct. If it exists, ...
57 votes
136 answers
19k views

Is this number evil?

Introduction In number theory, a number is considered evil if there are an even number of 1's in its binary representation. In today's challenge, you will be identifying whether or not a given number ...
13 votes
4 answers
683 views

Doors and guards

Related but noticeably different. You are the leader of the guard in the dungeon of an ancient castle. There are N doors in the dungeon and ...
16 votes
5 answers
811 views

Return of the Hydra Slayer

Its been a while since you killed that hydra, you basked in the glory for years, but now people are calling you washed up, a has been. Well its time you prove them wrong, you've heard the whereabouts ...
32 votes
43 answers
4k views

Print an arch of ascending / descending numbers

I figured an "arch" was the best way to describe this pattern of numbers: ...
60 votes
153 answers
6k views

Evolution of OEIS

In this challenge, the goal is to recreate the On-Line Encyclopedia of Integer Sequences one sequence at a time. Similar to the Evolution of Hello World, each answer depends on a previous answer. ...
43 votes
17 answers
3k views

{Curly Numbers};

In the esoteric programming language Curly, programs consist solely of curly braces {} and semicolons ;. Despite this humble ...
34 votes
59 answers
5k views

Sum every second digit in a number

I have a number like this: n = 548915381 The output should be the sum of every second digit of that number. In this case 26: ...
37 votes
29 answers
6k views

Find the number in the Champernowne constant

Introduction In base 10, the Champernowne constant is defined by concatenating representations of successive integers. In base 10: 0.1234567891011121314151617... ...
34 votes
44 answers
4k views

Find a multiple of a given number whose decimal representation looks like binary

I have come across a question on the Code Review site that seems interesting. I think OP is doing it wrong, but cannot be sure... So let's solve it for him! (write a program, not a function/procedure) ...
24 votes
61 answers
3k views

Subtract my odds from my evens

Given a non-negative integer, return the absolute difference between the sum of its even digits and the sum of its odd digits. Default Rules Standard Loopholes apply. You can take input and provide ...
32 votes
29 answers
2k views

Natural construction

The natural numbers including 0 are formally defined as sets, in the following way: Number 0 is defined as the empty set, {} For n ≥ 0, number n+1 is defined as n ∪ {n}. As a consequence, n = {0, 1, ...
85 votes
222 answers
17k views

Sum of all integers from 1 to n

I'm honestly surprised that this hasn't been done already. If you can find an existing thread, by all means mark this as a duplicate or let me know. Input Your input is in the form of any positive ...
87 votes
226 answers
16k views

Count up forever

Write a program that counts up forever, starting from one. Rules: Your program must log to STDOUT or an acceptable alternative, if ...
34 votes
84 answers
4k views

Swap the parity

Task Given a positive integer n, output n+1 if n is odd, and output ...
23 votes
36 answers
2k views

Output "Fit" numbers

"Fit Numbers" Sam has a "brilliant" idea for compression! Can you help? Here is a rundown of Sam's compression scheme. First take in a base 10 representation of any natural number strictly smaller ...
41 votes
81 answers
5k views

As Easy as One-Two-Three

Write a program or function that takes in a positive integer. You can assume the input is valid and may take it as a string. If the number is any of ...
49 votes
25 answers
5k views

Ginormous number

Output this 1364-digit base-10 number: ...
24 votes
24 answers
2k views

Decipher a squashed sequence

Given a string containing a sequence of ascending consecutive positive integers, but with no separators (such as 7891011), output a list of the separated integers. ...
26 votes
44 answers
3k views

X Steps Forward, 1 Step Back

Here the first 100 numbers of an easy sequence: ...
23 votes
11 answers
3k views

Highly composite numbers

A highly composite number is a positive integer that has more divisors than any smaller positive integer has. This is OEIS sequence A002182. Its first 20 terms are ...
45 votes
77 answers
7k views

Is this number triangular?

Challenge Given a positive integer, determine whether it is a triangular number, and accordingly output one of any two constant, distinct values. Definition A triangular number is a number that can be ...
12 votes
26 answers
2k views

Calculate all the squares up to x using only addition and subtraction

The goal is to calculate all the squares up to x with addition and subtraction. Rules: The code must be a function which takes the total number of squares to ...
55 votes
160 answers
10k views

Stay away from zero

Task Given a non-negative integer n, output 1 if n is 0,...
26 votes
26 answers
3k views

How far from binary?

Given a decimal integer n as input, output the smallest (in terms of absolute value) decimal integer m such that the absolute ...
39 votes
26 answers
2k views

Basic ASCII Tallies

Alternate Title: Tally Your Prison Sentence on the Wall Given a number n, output tallies grouped into the traditional 5-per-group and 50 per row. Examples 1 ...
23 votes
64 answers
4k views

count ones in range

Challenge : Count the number of ones 1 in the binary representation of all number between a range. Input : Two non-decimal positive integers Output : The sum of ...
21 votes
34 answers
2k views

Reversed Squares

Given an integer n, your task is to determine whether it is a perfect square that when reversed, is still a perfect square. You may assume n is always positive. When numbers such as 100 (10x10) are ...
29 votes
39 answers
4k views

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. ...
169 votes
73 answers
25k views

How high can you count?

Challenge: Your task is to write as many programs / functions / snippets as you can, where each one outputs / prints / returns an integer. The first program must output the integer ...
192 votes
180 answers
20k views

What is the smallest positive base 10 integer that can be printed by a program shorter (in characters) than itself?

I think the question as above is clear, but just in case: Write a full program (not just a function) which prints a positive base 10 integer, optionally followed by a single newline. Qualifying ...

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