78 questions linked to/from Is this number a prime?
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### Am I a Sophie Germain prime? [duplicate]

A Sophie Germain Prime is a prime number P such that 2P+1 is prime as well. Given a prime number as input, your task is to determine whether it is a Sophie Germain Prime. Standard Input/Output rules ...
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### Prime numbers between n and 2n [duplicate]

Bertrand's postulate states that there is always at least 1 prime number between n and 2n for all n greater than 1. Challenge Your task is to take a positive integer n greater than 1 and find all of ...
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### Check If my String is Prime [duplicate]

We define a prime character as a character that has a prime ASCII value. We define a prime string as a String that only contains prime characters. Given a String that only contains printable ASCII, ...
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### Primes, as efficiently inefficient as possible [duplicate]

Write a program that tests if a number n is prime by checking that none of the integers between 2 and ...
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### Prime decimal representations of prime binary numbers [duplicate]

Problem Statement: Consider a number n in base-10. Find the smallest base-10 integer i greater than ...
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### "Hello, World!"

So... uh... this is a bit embarrassing. But we don't have a plain "Hello, World!" challenge yet (despite having 35 variants tagged with hello-world, and counting). While this is not the most ...
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### Golf you a quine for great good!

Using your language of choice, golf a quine. A quine is a non-empty computer program which takes no input and produces a copy of its own source code as its only output. No cheating -- that means ...
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### Shortest infinite loop producing no output

Your task is to create the shortest infinite loop! The point of this challenge is to create an infinite loop producing no output, unlike its possible duplicate. The reason to this is because the code ...
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### Implement a Truth-Machine

A truth-machine (credits goes to this guy for coming up with it) is a very simple program designed to demonstrate the I/O and control flow of a language. Here's what a truth-machine does: Gets a ...
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### 1, 2, Fizz, 4, Buzz

Introduction In our recent effort to collect catalogues of shortest solutions for standard programming exercises, here is PPCG's first ever vanilla FizzBuzz challenge. If you wish to see other ...
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### Is this even or odd?

Note: There is not been a vanilla parity test challenge yet (There is a C/C++ one but that disallows the ability to use languages other than C/C++, and other non-vanilla ones are mostly closed too), ...
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### Golf all the 16 logic gates with 2 inputs and 1 output!

For example, the gate A and B is a logic gate with 2 inputs and 1 output. There are exactly 16 of them, because: each logic gate takes two inputs, which can be ...
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### List of primes under a million

This is my first code golf question, and a very simple one at that, so I apologise in advance if I may have broken any community guidelines. The task is to print out, in ascending order, all of the ...
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### Tips for golfing in Java

Are there any useful shortcuts that can be used in Java? As shown below, import already adds at least 17 characters to a program. ...