“Geometry is the knowledge of the eternally existent.”—Plato, , ca. 380 BCE Ancient peoples around the world navigated the seas, built wonders of engineering, and measured time with amazing precision. How were they able to do all of this without calculators or digital computers? One technology made it all possible: computing. The earliest evidence of counting is tally sticks from around 35000 BCE. Since then, societies worldwide developed complex mathematics to achieve difficult feats of calculation and engineering. Math fields like arithmetic, algebra, and geometry were used for surveying land, measuring the weight of gold, and even building the pyramids. Some ancient creations—such as the mysterious Antikythera device—are so complex archeologists are still fascinated by them. From base-10 to the abacus, learn about the ancient computation methods that formed the basis for smartphones and digital computers.