I received only two correct answers, from Tishyaa Chaudhry and Smiti Mittal – both brilliant kids – well done!

While brute force can help you arrive at the answer, the fun is in finding a method. The complete answer is at:

http://www.educreations.com/lesson/view/solution-to-puzzle-34/11869357/?s=zyLKl8&ref=link

Hope you enjoyed the puzzle!