India, May 18 -- Brain teasers have long been celebrated for their ability to engage the mind and sharpen reasoning skills. Whether shared over morning coffee or debated in comment threads online, these puzzles often challenge us to think outside the box. The latest to capture social media's attention? A math teaser involving a cow and a series of trades.

The post shared on X (formerly Twitter) features a seemingly simple scenario involving the buying and selling of a cow. It reads, "I bought a cow for $900. I sold it for $1200. I bought it again for $1300. I sold it again for $1600. How much did I earn?" At first glance, the question appears straightforward, prompting users to do a basic profit-and-loss calculation. However, the sequenc...