1.   And, most challenging, he had to wrestle with complex mathematics to explain how the codes were broken.

2.   Implanted microprocessors, for instance, could give us better vision or control over our emotions, or the ability to easily understand complex mathematics.

3.   It includes not only the Olmecs, Mayas and Aztecs, but also several other cultures that developed highly sophisticated art forms, writing systems and complex mathematics.

4.   The Nazca carved enormous designs in the desert sand, requiring hundreds of thousands of man-hours and knowledge of complex mathematics.