Daily Challenge #38

Determine if a number is Prime Number
Create a procedure that will determine if a number is Prime number (true) or not (false)


isPrime(2) -> True
isPrime(14) -> false

The first 20 primes are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, and 71


  • Use Procedure with return
  • Procedure takes single number
  • Returns True (if prime) or False (if not)
  • Should not use any extensions
  • Use only numbers 1 to 200

Sample Java program - use this for your logic:

Java Program to Check Whether a Number is Prime or Not


that’s all, but this may not be the desired solution of Hossein

but why should I reinvent the wheel? :wink:

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:sweat_smile: Don’t use extension (will add that into requirements). The whole challenge is to code by yourself :slight_smile: to come up with solutions

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Ok, I guessed that

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What that % mean I know that is reminder but I didn’t understand can you explain sir please

That’s modulo operation. Use Math modulo block. wiki


I did not test it:


20 Blocks


Well done…
But take a deep look at java code.

Already used the same logic!

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I know but variables declaration/initialization can be improved either in example code or your blocks.

@ravigarg Very good job. You need to add the logic for number 1. Try your procedure and see what you get for procedure(1)

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additional challenge: if you got it working for smaller numbers you might want to check, if your solution still works for larger numbers, for example 104729 or even 15485863…

question: why does it not work for larger numbers anymore? And how could this be fixed?


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It did work, but for the second number i.e. 15485863 I had to wait for 4-5 minutes.

It does, but dividing long numbers again and again with long numbers take a lot of time and makes a situation of an infinite loop.

Still Thinking on this one!

Thanks! WIll surely add that.

Updated requirements as above :point_up_2:

So, is this the final solution
I ADDED the check if no is 1,0.


Solved by both @bodymindpower and @ravigarg

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