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Questions tagged [number]

This challenge is intended to be solved by using, manipulating, accepting as input, or outputting numeric values.

23
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18answers
1k views

The Digit Triangles

Challenge: Input: A positive integer \$n\$ Output: Create a list in the range \$[1,n]\$, and join it together to a string (i.e. \$n=13\$ would be the string ...
10
votes
9answers
413 views

New Order #1: How does this feel?

Introduction Putting all positive numbers in its regular order (1, 2, 3, ...) is a bit boring, isn't it? So here is a series of challenges around permutations (reshuffelings) of all positive numbers. ...
30
votes
19answers
2k views

Convert number to a base where its representation has most “4”s

Inspired by this. There is a number, given as either integer, string or array of digits (your choice). Find the base in which the representation of the number will have most "4"s and return that base. ...
14
votes
48answers
4k views

Print the amount of ones in a binary number without using bitwise operators

Description Given a number, print the amount of 1s it has in binary representation. Input A number >= 0 in base 10 that ...
69
votes
37answers
12k views

Am I a Rude Number?

For a while now, I've been running into a problem when counting on my fingers, specifically, that I can only count to ten. My solution to that problem has been to count in binary on my fingers, ...
57
votes
42answers
6k views

Is it a Cyclops number? “Nobody” knows!

Task: Given an integer input, figure out whether or not it is a Cyclops Number. What is a Cyclops number, you may ask? Well, it's a number whose binary representation only has one ...
27
votes
26answers
2k views

Make a (somewhat) self-referential string

You want to make a string where the (1-indexed) character at index n is n. When n is less ...
12
votes
17answers
2k views

Codegolf Rainbow : Draw in Black-and-White

Introduction: (Source: Wikipedia) When we look at a rainbow it will always have the colors from top to bottom: Red; orange; yellow; green; blue; indigo; violet If we look at these individual rings, ...
189
votes
282answers
42k 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 ...
35
votes
71answers
4k 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 ...
30
votes
23answers
7k views

Could you please stop shuffling the deck and play already?

Challenge: Input: A list of distinct positive integers within the range \$[1, \text{list-size}]\$. Output: An integer: the amount of times the list is riffle-shuffled. For a list, this means the ...
-1
votes
1answer
95 views

Sort a list of Numbers as letters [on hold]

So, you have a random list (random meaning it doesn't matter what order it is in) of numbers with a length of n, where n is a positive integer smaller than 1000 and ...
38
votes
19answers
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, ...
6
votes
24answers
524 views

Sum integers in a string

Input A string. Output The sum of all integers in the line. Constraints 1≤Length of line≤500 Sample test Case Input the 5is 108 seCONd4 a Output ...
28
votes
43answers
8k views

Am I not good enough for you?

Background: The current Perfect Numbers challenge is rather flawed and complicated, since it asks you to output in a complex format involving the factors of the number. This is a purely decision-...
19
votes
25answers
2k views

The Highest Dice

Challenge: Here we have the first 100 items of a sequence: ...
34
votes
64answers
3k views

Interleave numbers from 1 to n, with the same numbers reversed

A simple one: Take a positive integer n less than 1000, and output the integers from 1 to n interleaved with the integers from n to 1. You must concatenate the numbers so that they appear without any ...
30
votes
24answers
5k views

The (Easy) Road to Code

Input: An integer \$n\$, which is guaranteed to be \$\ge3\$. An integer \$d\$, which is one of \$[-1,0,1]\$. Output: A road of size \$n\$, which will be in a north-west direction if \$d=-1\$; a ...
-2
votes
0answers
104 views

Experiment Design [closed]

Background I’ve had to make some of these by hand for a science experiment and was checking to see if anybody had any clever ways of achieving this. It feels like sudoku, but not quite. figuring ...
16
votes
27answers
2k views

Convert from base 10 to base 2 without built-in base conversions

Background: You have been given an assignment to convert base 10 numbers to base 2 without using any premade base conversion functions. You can't use any imported libraries either. Problem: ...
29
votes
29answers
7k views

Chicken McNugget Numbers

Description Chicken McNugget numbers are numbers that can be expressed as a sum of 6, 9 or 20 - the initial sizes of the famous Chicken McNuggets boxes sold by McDonald's. In that sum, a number may ...
32
votes
55answers
5k 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 ...
11
votes
14answers
1k views

Maximum Maxima!

Inspired by this question and refined by Luis Mendo. Challenge Given a 2D matrix of integers, each row has a maximum value. One or more elements of each row will be equal to the maximum value of ...
10
votes
13answers
926 views

Multiply and Divide

Given a value x find the smallest numerical value greater than y that is capable of being multiplied and divided by x while retaining all original digits. The new numbers do not lose digits. The new ...
25
votes
21answers
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−p. ...
20
votes
15answers
2k views

Square Root Distance from Integers

Given a decimal number k, find the smallest integer n such that the square root of n is ...
32
votes
44answers
4k views

Print all lexicographically increasing numbers under 10000

A lexicographically increasing number is an integer whose digits are in strictly increasing order. Print all lexicographically increasing numbers under 10000. Here are lines of the expected output: ...
22
votes
21answers
3k views

Bertrand's Primes

Bertrand's Postulate states that for every integer n ≥ 1 there is at least one prime p such that n < p ≤ 2n. In order to verify this theorem for n < 4000 ...
2
votes
7answers
332 views

Countries by Area

Challenge Given two non negative integers a < b, output all countries, from the below Top 100 Countries, where area is between ...
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 ...
24
votes
27answers
2k views

Magnanimous numbers

Given an positive integer as input determine if it is a magnanimous number. A magnanimous number is a number such that any insertion of a + sign between any two ...
37
votes
75answers
6k views

Is this number a factorial?

The Task Given a natural number as input, your task is to output a truthy or falsey value based on whether the input is a factorial of any natural number. You can assume that the input number will ...
22
votes
9answers
2k views

Determine the Base where a Given Equation is True

Given 3 integers, determine the lowest possible base for the first two integers to multiply into the third. If you think of the Answer to the Ultimate Question of Life, The Universe, and Everything, 6 ...
26
votes
81answers
4k views

Is it a whole number?

A number is whole if it is a non-negative integer with no decimal part. So 0 and 8 and ...
52
votes
75answers
9k views

Do n and n^3 have the same set of digits?

Given a number n (0 <= n <= 2642245), check if n and n3 have the same set of digits, and output a truthy or falsey value accordingly. For example, let's check the number 100. 1003 is 1000000. ...
24
votes
16answers
1k views

Sums of prime factors

2013 has the prime factorization 3*11*61. 2014 has the prime factorization 2*19*53. An interesting property regarding these ...
5
votes
3answers
491 views

A Multipurpose Quine

I personally love quines, but they all seem to be so... static. So why not create a quine that can do more. Challenge The challenge here is to create a quine that without any sort of input is a ...
12
votes
18answers
899 views

Jumping Numbers

A jumping number is defined as a positive number n which all pairs of consecutive decimal digits differ by 1. Also, all single digit numbers are considered jumping numbers. eg. 3, 45676, 212 are ...
39
votes
60answers
6k views

It's Hip to be Square

Challenge So, um, it seems that, while we have plenty of challenges that work with square numbers or numbers of other shapes, we don't have one that simply asks: Given an integer ...
70
votes
181answers
12k 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 ...
16
votes
6answers
866 views

The Binary Fences

Input: An integer n in the range 2 <= n <= 10 A list of positive integers Output: Convert the integers to their binary ...
11
votes
1answer
716 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, ...
37
votes
64answers
5k views

Am I divisible by double the sum of my digits?

Given a positive integer as input, your task is to output a truthy value if the number is divisible by the double of the sum of its digits, and a falsy value otherwise (OEIS A134516). In other words: ...
38
votes
45answers
4k views

Scrabble scorer

Challenge: Take a string of upper or lower case letters as input (optional), and calculate the score that string would get in a game of Scrabble in English. Rules: The score of each letter is as ...
26
votes
22answers
3k views

Find the next 1-sparse binary number

A positive integer N is K-sparse if there are at least K 0s between any two consecutive 1s in its binary representation. So, the number 1010101 is 1-sparse whereas 101101 is not. Your task is to ...
15
votes
45answers
2k views

Print the Lost numbers

As a big fan of the Lost TV series, I always got intrigued by the sequence of numbers that repetitively appears on the episodes. These numbers are: \$ 4, 8, 15, 16, 23, 42\$ (A104101) Using any ...
23
votes
41answers
2k views

Encode the alphabet cipher

Given a string that contains only lowercase letters, encode that string with the alphabet cipher. To encode with the alphabet cipher (I will be using the example ...
16
votes
23answers
2k views

Is this a Hardy-Ramanujan-Number-ish Harshad Number?

Background The number 1729 is the Hardy-Ramanujan number. An amazing property of it was discovered by S. Ramanujan (who is widely regarded as the greatest Indian mathematician1), when G.H. Hardy paid ...
22
votes
16answers
1k views

Sort a number's divisors by prime factorization

Given an input of an integer ≥ 2, output a list of its divisors sorted by the exponents in their prime factorizations, in ascending order, ordering first by the largest prime, then by the second ...
23
votes
17answers
4k views

The real treasure was the numbers we made along the way

Your task is to write a program, function or snippet (yes, snippets are allowed) that simply outputs an integer. However, you must be able to separate your submission into prefixes that also produce ...