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

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http://cheatsheetgmat.com

All GMAT Math Formulas you need to succeed!