feat: Add FindPrimeNumber class with prime check using loop

WHAT the code does:
- Defines `FindPrimeNumber` class with static method `isPrime(int n)`.
- `isPrime()`:
  - Loops from `2` to `n/2 - 1`.
  - If any number divides `n`, returns `false`.
  - Otherwise returns `true`.
- `main()`:
  - Uses `Scanner` to read an integer from the user.
  - Calls `isPrime()` and prints `true` if prime, `false` otherwise.

WHY this matters:
- Demonstrates a classic algorithm for **prime number detection**.
- Combines user input handling with logic-based computation.
- Introduces conditionals and loops for factor checking.

HOW it works:
1. User enters a number (e.g., `19`).
2. Loop checks divisibility from `2` up to `n/2`.
3. If divisor found, immediately returns `false`.
4. If no divisor found, returns `true`.

Tips & gotchas:
- Algorithm has inefficiency:
  - Checking up to `n/2` is unnecessary; prime check only requires testing divisors up to `√n`.
- Edge cases not handled:
  - `n <= 1` should return `false` (not prime).
  - `n = 2` or `n = 3` should return `true`, but loop may fail correctly for `2`.
- Always close `Scanner` (`scanner.close()`).
- Output is just `true`/`false` → could be more user-friendly messages.

Use-cases:
- Educational demo for prime-checking logic.
- Good interview practice for optimizing loop bounds (`√n` check).
- Foundation for prime-related problems (prime factors, sieve of Eratosthenes).
- Useful for competitive programming warm-ups.

Short key: algo-prime-check-basic-loop.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section10Methods/src/FindPrimeNumber.java

@@ -1,26 +1,25 @@
 /* A prime number is a positive integer having exactly two factors, i.e. 1 and the number itself.
 If p is a prime, then its only factors are necessarily 1 and p itself.
-Any number that does not follow this is termed a composite number, which can be factored into other positive integers.*/
+Any number that does not follow this is termed a composite number, which can be factored into other positive integers.
+*/
 
 import java.util.Scanner;
 
-public class FindPrimeNumber
-{
+public class FindPrimeNumber {
     static boolean isPrime(int n)
+    //true or false. initialize the method.
     {
-        for(int i=2; i<n/2;i++)
+        for(int i = 2; i<n/2; i++) //assign a value of i=2 and increment by 1 everytime when loop is running.
         {
-            if(n%i==0)
+            if(n % i == 0) //means n has a factor other than 1 and itself → not prime.
                 return false;
-        }
-        return true;
+        } return true;
     }
-    public static void main(String[] args)
-    {
-
+    public static void main(String[] args) {
         Scanner scanner = new Scanner(System.in);
         System.out.println("Enter a number to check prime or not: ");
+
         System.out.println(isPrime(scanner.nextInt()));
        /* System.out.println(isPrime((19)));*/
     }
-}
+}