This Man Can Solve Any Math Problem Using Straight Lines
This trick for multiplication using crossed lines has its origins in one of the oldest mathematical tools in the world. Centuries before the advent of the written modern numerical system, traders used a counting frame called the abacus to calculate trades and purchases. Similar abacuses were developed in Mesopotamian, Egyptian, Chinese, Indian, Russian and Native American tribes. The Mesopotamians are thought to be the originators of the device, with the Sumerian abacus first appearing around 2700 BCE. Today, the abacus is used primarily for teaching mathematics to blind children to overcome the lack of visual information. Tricks like this one are used today in Japan as a quick and easy way to start learning math.