DEV Community

Vivin Kingsly V
Vivin Kingsly V

Posted on

prime number

1. The Logic Building (The Strategy)

The general rule for a Prime number is that it’s only divisible by 1 and itself. However, I realized a common confusion: Composite numbers (like 4) are also divisible by 1 and themselves.

Prime Number (e.g., 5): When divided by every number from 1 to itself, it produces a remainder of zero exactly two times (1 and 5).

Composite Number (e.g., 4): It produces a remainder of zero more than two times (1, 2, and 4).

2. Recipe Writing (The Algorithm)

I treated my code like a recipe:

Input: Get the number.

Loop: Check every number from 1 up to the input number.

Check Remainder: Use the modulo operation (%) to find where the remainder is 0.

Counter: Count how many times the remainder was 0.

Final Result: If the count is exactly 2, it's Prime. Otherwise, it’s Composite.

3. The Ingredients (The Variables)

I gathered my "ingredients" for the Java code:

input: The number to check.

count: To track the number of divisors.

for loop:

Start:1(Initialization)
End:Input(Condition)
Next step:+1(Increment)

if-else: To handle the logic.

Program(Javascript):

var a = 24
var c = 0

for (i = 1; i <= a; i++)
{
if (a % i == 0)
{
c++
}
}

if (c == 2)
{
console.log("Prime")
}
else
{
console.log("Not Prime")

}

Top comments (0)