To calculate per-diem interest, take the interest rate (be sure to express it as a decimal, so 10% becomes 0.10) and divide by 365 to determine the daily interest rate.

For instance, all federal student loans charge simple interest. How to calculate amortizing interest on a loan Many lenders charge interest based on an amortization schedule.

To calculate how much you'll pay in simple interest, multiply the principal (P) by the interest rate (R) by the time period in years (T), then divide that number by 100.

How Simple Interest Works: An Example Suppose you take out a $5,000 loan at 6% interest for two years. To calculate the amount of interest you will pay, use the simple interest formula above.

Learn how to calculate the Simple Interest in Excel either for a single entry or a range or entries, between two dates, using this forumula.

The formula for calculating simple interest in a savings account is Interest = P * R * T. Multiply the account balance by the interest rate by the time period.

Learn how to calculate principal and interest on loans, including simple interest and amortized loans, and understand the impact on your monthly payments and loan costs.

The formula to calculate simple interest in a savings account is the deposit amount times the annual interest rate times the amount of time the money is deposited.

Calculating student loan interest can be pretty straightforward, but how you calculate it will vary depending on whether you’re dealing with simple or compound interest.

How to Find the Simple Interest Rate on a TI-83 Calculator. The TI-83 scientific calculator includes a finance-solving application that can do advanced calculations about the time value of money.