Marcus du Sautoy uses combinations of peaches and plums and a set of scales, to show how simultaneous equations can be solved. This method didn’t appear in the West until the 19th century, but had ...

Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Charlene Rhinehart is a CPA , CFE, chair of ...

Vikki Velasquez is a researcher and writer who has managed, coordinated, and directed various community and nonprofit organizations. She has conducted in-depth research on social and economic issues ...

Lindsey Ellefson is Lifehacker’s Features Editor. She currently covers study and productivity hacks, as well as household and digital decluttering, and oversees the freelancers on the sex and ...