**Average formula:**

Let a1,a2,a3,......,an be a set of numbers, average = (a1 + a2 + a3,+......+ an)/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: le…