Interest is defined as the "cost of borrowing money". There are two types of interest, simple and compound. In compound interest the interest amount is added back to the principle periodically so that future interest calculations include paying interest on interest!

## Compound Interset 101

Define your terms.

Any interest calculation will require you define several terms. You will need to know the following:

P = principal I = interest rate (as a decimal) N = the number of times the interest is compounded in a year (monthly=12, quartler=4, etc) T = time expressed as the number of years for the calculation A = Answer after T number of years!

Plug your terms in to the follow formula:

step 1) Divide I over N [I/N] step 2) Add 1 [1+ (I/N)] step 3) Multiply by P [ P(1+ (I/N)) ] save this number step 4) multiply N by T [ NxT ] step 5) raise the answer from 3 to the power of the answer to 4 [ans3^ans4]

example:

P = 1,000 I = .1 (10%) N = 4 (quarterly) T = 2

step 1) .1/4 = .025 step 2) 1+.025 = 1.025 step 3) 1,000 x 1.025 = 1025 step 4) 4x2 = 8 step 5) 1,025 ^ 8 = 1,218.40

1,218.40 is the total paid for a $1,000 loan at 10% after two years with quarterly. interest.

#### Tips

writing down your terms separate from your calculation will make the concept easier to grasp

#### Warnings

if you use 1 for N it will turn the calculation into a simple interest formula

Tips

- Writing down your terms separate from your calculation will make the concept easier to grasp.

Warnings

- If you use 1 for N, it will turn the calculation into a simple interest formula.

Writer Bio

Kelcey Lehrich has been writing for several online media outlets for the past few years. His work can be found on Electronista.com, Macnn.com and LeftLaneNews.com. Lehrich holds a bachelor's degree from Cleveland State University in business administration and finance.