Scientific American spoke to Rojas about this history, the deeply engaging humanity of mathematics and the egos at play in defining the mathematical language we take for granted today.

Create a series of equations to produce each number from 0 to 20, using just '4 Fours' in each equation, along with basic math symbols. Don't forget the standard order of operations, as you'll need to ...

Some people with math disabilities, however, who lack an intuitive understanding of numbers or symbols or place value, may struggle endlessly with these basic mathematical concepts.