As we learn the laws of arithmetic in school, we start out with the simple counting numbers 1, 2, 3,… in kindergarten, and expand into more complicated number systems as the need arises. When we learn about subtraction, we find there are problems that can’t be solved with counting numbers, so we learn about 0 and negative numbers. As we master division, we find that most problems require rational numbers to solve. When important applications required numbers like π and 2 https://s3-euw1-ap-pe-df-pch-content-public-u.s3.eu-west-1.amazonaws.com/9781315370972/7b591cbc-c286-415b-8cd2-e7cb428d30cf/content/eq1848.tif"/> , we considered the set of real numbers. Finally, as we studied quadratic equations, we found that some polynomials required complex numbers to be solved.