2-digit

below 100, 25 prime numbers are there, 25-4=21(4 means 2,3,5,7)

class Program {

    static int[] results = new int[25];
    static void Main(string[] args)
    {
        Console.WriteLine(GetAllPrime(out results));
        for (int i = 0; i < results.Count(); i++) 
        {
            Console.WriteLine("Number Prime is " + results[i]);

        }
        Console.ReadLine();

    }
    public static int GetAllPrime(out int[] result)
    {
        result = new int[25];
        int innerCount = 0;
        int finalCount = 0;
        for (int i = 10; i <= 99 ; i++) 
        {
            for (int j = 2; j <= i; j++) 
            {
                if (i % j == 0)
                    innerCount++;
            }
            if (innerCount == 1)
            {
                result[finalCount] = i;
                finalCount++;
            }
            innerCount = 0;
        }

        return finalCount;
    }
}

11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Javascript Solution

from  = parseInt(window.prompt("Starting From"));
to = parseInt(window.prompt("Up to"));
count = 0;

for(i=from; i<=to; i++){
    flag = false;
    for(j=2; j<=Math.sqrt(i); j++){
        if(i%j==0){
            flag = true;
            break;
        }
    }
    if(!flag){
        count++;
    }
}

alert("Total Prime numbers between " + from + " to " + to + " are " + count);