Adam Hayes, Ph.D., CFA, is a financial writer with 15+ years Wall Street experience as a derivatives trader. Besides his extensive derivative trading expertise, Adam is an expert in economics and ...

Principal is the amount you borrowed, and interest is the amount you pay to the lender as a charge for borrowing. To calculate interest, multiply the principal amount by the interest rate, then ...

Money borrowed from commercial banks comes at a cost. This extra amount of money that a borrower has to pay back is known as interest, and the original sum is called principal. And the rate at which a ...

Calculating the interest rate on a personal loan can be difficult. Most lenders use simple interest rather than compound interest, though, which makes the job a little easier. To calculate how much ...