Questions tagged [number]

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

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17 votes
31 answers
2k views

Finding Not-Quite-Prime Numbers

Your challenge, should you chose to accept it, is to code-golf a function that returns true or false (or some similar meaningful representation of yes and no) if a number meets the following criteria: ...
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  • 2,419
7 votes
27 answers
5k views

determine longest group of consecutive numbers

INPUT: 10 random numbers each number is greater than 0 and less than 100 list of numbers is presorted, lowest to highest the list will not contain any duplicate numbers CHALLENGE: Write a function ...
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  • 205
2 votes
17 answers
730 views

The group of sequential positive numbers with the highest sum?

Given the following list of numbers, find the group of sequential positive numbers with the highest sum. Example input: 12 2 35 -1 20 9 76 5 4 -3 4 -5 19 80 32 -1 ...
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13 votes
47 answers
6k 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 ...
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  • 829
1 vote
13 answers
1k views

position of the only 1 in a number in binary format [closed]

Every number of the form 2i (where i is a non-negative integer) has a single 1 in its binary representation. Given such a number, output the 1-based position of the ...
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5 votes
16 answers
2k views

Hexadecimal To Decimal [closed]

Read input of up to 8 characters presented as hexadecimal number and print this number as decimal number. In case that input can not be presented as hexadecimal input it has to print 0 Rules: It is ...
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  • 283
13 votes
47 answers
3k views

Enumerate all palindromic numbers (in decimal) between 0 and n

Given a non-negative integer n, enumerate all palindromic numbers (in decimal) between 0 and n (inclusive range). A palindromic number remains the same when its digits are reversed. The first ...
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  • 324
10 votes
26 answers
2k views

Machine Epsilon

Machine epsilon is an important floating point number to know when doing numerical calculations. One way to understand it is when this relation ...
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  • 341
31 votes
63 answers
16k views

Shortest way to reverse a number [closed]

Write a function (or equivalent subprogram) to accept a single integer valued argument and return a (similarly typed) value found by reversing the order of the base-10 digits of the argument. For ...
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7 votes
7 answers
550 views

Formatting numbers

Today computers use millions of bytes of memory, and decimal or hexadecimal notations get less and less informative. Most human-readable formatting just display the number with the highest unit ...
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  • 171
10 votes
2 answers
604 views

The Prime Grid Game

I had fun solving this, so I offer this golf challenge. The objective of this golf is to find the largest prime number that can be constructed using the given instructions. You should accept 3x3 ...
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  • 2,140
5 votes
4 answers
2k views

Amicable number calculator [closed]

Write a program that calculates amicable numbers, starting from [0,0], intil the maximum value for an integer is reached in the language you chose to write it in. Amicable numbers are two different ...
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17 votes
9 answers
882 views

Last k digits of Powers of 2

For any integer \$r\$, there exists a power of 2 each of whose last \$r\$ digits are either 1 or 2. Given \$r\$, find the smallest \$x\$ such that \$2^x\bmod{10^r}\$ consists of only 1 or 2. For \$r=...
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  • 2,140
10 votes
9 answers
5k views

Arbitrary Base Conversion [closed]

Create a routine that takes an array of blocks in one numeric base system, and convert them to an array of blocks in another numeric base system. Both the from and to systems are arbitrary and should ...
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  • 919
9 votes
2 answers
1k views

Floating point addition, without floats!

Your task is to write a program, in any language, that adds two floating point numbers together WITHOUT using any fractional or floating point maths. Integer maths is allowed. Format The format for ...
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  • 1,103
5 votes
8 answers
290 views

Power modulo golf. [closed]

Write a function f(a,b,c) that calculates a^b (mod c) in less than 10 seconds. a, b < 10^100 c < 10000. examples: ...
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  • 5,438
14 votes
6 answers
5k views

Calculate the last digits of Graham's Number

Graham's number ends in a 7. It is a massive number, in theory requiring more information to store than the size of the universe itself. However it is possible to calculate the last few digits of ...
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  • 3,262
11 votes
18 answers
764 views

Output nearby primes

Write a program which takes an input (which may or may not be prime), and lists the immediate prime following and preceding it. Example input: 1259 Example ...
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  • 3,262
13 votes
5 answers
626 views

Perfect powers in more than one way?

Challenge Your task is to write a program or function which, given a positive integer \$N\$, finds all positive integers less than or equal to \$N\$ that can be expressed as a perfect power in more ...
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  • 4,453
3 votes
6 answers
432 views

Minimum of last k [closed]

Write a function that takes two arguments: a number k and a list l, and that returns another list ...
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  • 5,906
6 votes
33 answers
3k views

Print largest integer you can with the fewest characters [closed]

Find a way to output a large integer with few characters. Solutions will be scored based on the magnitude of the number and shortness of code. EDIT: Let's impose a time limit of a minute on sensible ...
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  • 12.2k
145 votes
304 answers
38k 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 ...
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