standard_description: Know there is a complex number i such that i^(2) = –1, and every complex number has the form a + bi with a and b real.
problem_activity: Task
About how many cells are in the human body?
You can assume that a cell is a sphere with radius 10$^{-3}$cm and that the density of a cell is approximately the density of water which is 1g/cm$^3$.


aligns: no