If you want to achieve a good score on the math section then it is necessary that you memorize the necessary GMAT math formulas.

GMAT Maths formulae

Algebra Formulas

Exponential Equations

xn*xm = xn + m
(xn)/(xm) = x n - m
(x/y)n = (xn)/(yn)
xn*yn = (xy)n
(xy)z = xyz
x-n = 1/(xn)
1n = 1
x0 = 1
0n = 0, except 00 = 1 or undefined
FV = CV(1 + g)T
Examples

Quadratic Equations

ax2 + bx + c = 0.
quadratic formula

Interest

Simple Interest = P*r*t
P = starting principle; r = annual interest rate; t = number of years
Annual Compound Interest = P(1+r)t
Compound Interest = P(1 + r/x)xt x = number of times the interest compounds over the year

Other

Distance = Rate*Time
Wage = Rate*Time
Arithmetic Formulas

Combinatorics

Combinations:nCk = n!/((n-k)k!)!
Permutations:nPk = n!/(n-k)!
Circular: (n-1)!
k = number of objects selected from a pile of n objects
n = total number of objects from which k objects can be selected

Fractions

(a/b)/(c/d) = (a/b) * (d/c)

Percents

Percent Change, as a decimal = (New - Old)/Old
N = (1 + G)O; N = New Value, 0 = Old Value, G = Growth Rate as decimal

Probability

Probability that event E occurs = P(E) = (Number of outcomes in E) / (Total number of possible outcomes)
P(not E) = 1 - P(E)
P(E or F) = P(E) + P(F) - P(E and F)
P(E and F) = P(E)P(F)

Angles

Sum of Interior Angles of Polygon = (n-2)(180)
n = number of sides of a polygon
Central Angle = 2(Inscribed Angle)

Area

Square: A = a2
Rectangle: A = lw
Parallelogram: A = bh
Trapezoid: A = .5(a+c)h, where a and c are the lengths of the parallel sides

Circles

π = pi = 3.1415
Area: A = πr2
Circumference: C = 2πr
Central Angle = 2(Inscribed Angle)
Area of Sector = (x/360)πr2

Perimeter

Square: P = 4l
Rectangle: P = 2w + 2l
Parallelogram: P = 2b + 2a, where a and b are the lengths of the non-parallel sides
Circle: P = 2πr

Triangles

Area: A = .5bh
Pythagorean Theorem: A2 + B2 = C2 where A = one leg, B = the other leg, C = hypotenuse

Volume

Cube: V = a3 where a is the length of a side
Rectangular Solid: V = hwl
Cylinder: V = πr2h