When Manuel "Manny" Medina was a senior product manager at Amazon in 2003, he noticed something: Nearly all of the executives could solve difficult mathematical equations without using a calculator or even a pencil.

"The executives at Amazon and all the [vice presidents] were able to do math in their head really quickly," he says. "It was so stark, their ability to manage numbers so quickly."



Medina realized that if we wanted to get ahead, he needed to get more comfortable working with numbers in his head. He bought a book on speed math to "just keep up with them."

While having strong math skills is often a prerequisite for professionals in the tech or finance world, being comfortable with numbers can help employees in other industries, Medina says.