**Average formula:**

Let a

_{1},a

_{2},a

_{3},......,a

_{n}be a set of numbers, average = (a

_{1}+ a

_{2}+ a

_{3},+......+ a

_{n})/n

**Fractions formulas:**

Converting a mixed number to an improper fraction:

Converting an improper fraction to a mixed number:

**Formula for a proportion:**

In a proportion, the product of the extremes (ad) equal the product of the means(bc),

Thus, ad = bc

**Percent:**

Percent to fraction: x% = x/100

Percentage formula: Rate/100 = Percentage/base

Rate: The percent.

Base: The amount you are taking the percent of.

Percentage: The answer obtained by multiplying the base by the rate

**Consumer math formulas:**

Discount = list price × discount rate

Sale price = list price − discount

Discount rate = discount ÷ list price

Sales tax = price of item × tax rate

Interest = principal × rate of interest × time

Tips = cost of meals × tip rate

Commission = cost of service × commission rate

**Geometry formulas:**

**Perimeter**:

__Perimeter of a square__: s + s + s + s

s:length of one side

__Perimeter of a rectangle__: l + w + l + w

l: length

w: width

__Perimeter of a triangle__: a + b + c

a, b, and c: lengths of the 3 sides

**Area:**

__Area of a square__: s × s

s: length of one side

__Area of a rectangle__: l × w

l: length

w: width

__Area of a triangle__: (b × h)/2

b: length of base

h: length of height

__Area of a trapezoid__: (b

_{1}+ b

_{2}) × h/2

b

_{1}and b

_{2}: parallel sides or the bases

h: length of height

**volume:**

__Volume of a cube__: s × s × s

s: length of one side

__Volume of a box__: l × w × h

l: length

w: width

h: height

__Volume of a sphere__: (4/3) × pi × r

^{3}

pi: 3.14

r: radius of sphere

__Volume of a triangular prism__: area of triangle × Height = (1/2 base × height) × Height

base: length of the base of the triangle

height: height of the triangle

Height: height of the triangular prism

__Volume of a cylinder__:pi × r

^{2}× Height

pi: 3.14

r: radius of the circle of the base

Height: height of the cylinder