This chapter presents a list of symbols used within all branches of mathematics to express a formula or to represent a constant. It shows a set of symbols, abbreviations, and their meanings commonly employed in Mathematics. Mensuration is all about the method of quantifying. The measurement results got using mensuration are mere approximations. A polygon is a plane figure which is surrounded by a fixed number of straight line segments closing in a loop. There are two types of polygons— regular and irregular polygons. A regular polygon has equal sides and equal angles. A polygon with unequal sides and unequal angles is called an irregular polygon. The chapter explores some commonly used algebraic formulae. Trigonometry is a branch of mathematics which treats the properties of angular functions and their application to the solution of triangles. A matrix is a rectangular array of numbers, symbols, or expressions, arranged in rows and columns.