This riddle has been around for some time on internet platforms such as Instagram, Facebook, and WhatsApp, and many people still argue over what the answer might be, as there are many possibilities. The correct answer is The minimum number of weights required is five and these should weight 1, 3, 9, 27 and 81 pounds. The merchant has to use a balance weighing scale to do the job. To weigh 2 pounds, he’ll have to put the 3 pound weight on one pan and 1 pound weight on the other pan. To weigh 5 pounds, he’ll have to put the 9 pound weight on one pan and 1 and 3 pound weights on the other pan.