Walter took Ethel to the state fair every year, and every time he would say to her, “Ethel, you know that I’d love to go for a ride in that helicopter.” But Ethel would always reply, “I know that...

Have you ever come across a math puzzle on social media that seems so easy, yet almost everyone gets it wrong? This classic puzzle claims to be an official interview question from Google. It looks like a simple arithmetic test, but...