I can suggest you to check out GMAT Cheat Sheet, this is an excerpt from the website:GMAT Cheat Sheet: What math formulas are covered?
Properties of numbers – rules of divisibility, primes, consecutive integers
Exponents, squares and roots – adding, subtracting, simplifying
Inequalities – testing, reciprocals, extreme values, squaring
Equations – factoring and distributing, substituting, quadratic formula
Word translations – age charts, prices and quantities, rate and time
Decimals and fractions – counting, comparing, computations, percentages
Geometry – polygons, circles, cylinders, triangles, three-dimensional forms
All GMAT Math Formulas you need to succeed!