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Ruby program to find the given number is PRIME or not using recursion

Last Updated : December 15, 2025

Problem Solution

In this program, we will read an integer number from the user and find the input number is PRIME or not using recursion.

Program/Source Code

The source code to find the given number is PRIME or not using recursion is given below. The given program is compiled and executed successfully.

# Ruby program to find the given number 
# is PRIME or not using recursion

def checkPrime(num, i)
    if (i == 1)
        return 1;
    else
       if (num % i == 0)
         return 0;
       else
         return checkPrime(num, i - 1);
       end    
    end
end

print "Enter number: ";
number = gets.chomp.to_i;  

result = checkPrime(number, number/2);

if result==1
    print "Given number is PRIME number.";
else
    print "Given number is not PRIME number.";
end

Output

Enter number: 11
Given number is PRIME number.

Explanation

In the above program, we read an integer number from the user. Then we found the input number is PRIME or not using recursive function checkPrime(). Then we printed the result.

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