Even though it ought to be impossible, the square of the number i is minus one. That formula led us to create complex numbers, which led to complex analysis, one of the most powerful areas of mathematics. With the help of complex numbers, mathematicians improved methods to calculate trigonometric tables, found more powerful methods to understand waves, heat, electricity, and magnetism, and the mathematical basis of quantum mechanics.

## The Formula to Get 42 Billion Digits of π

While writing "7 Utterly Well-written Math Books About Pi," I found a very interesting math formula that will give you 42 consecutive digits of π accurately but is still wrong.