Has to be the invention of 0 by the indian mathematician Aryabhata. Without it mathematics would be nothing. There would be no 'nothing in maths', 0 is the solution in which mathematics revolve. Calculus, Intergration, Differenciation, Polynomials, Measurement, Pyathagoras' Theorem, Applied Maths, Probablity, Graphs, Geometry, Matrices, Circle theorems, Indices, Consumer Arithmetic, Surds, Word Problems and etc. all come after this vital concept.