This will return a periodic interest rate of 2.21 percent. Note that the "type" and "guess" arguments were omitted and were thus set to their defaults of "0" and "0.10" respectively. References ...

Periodic interest rate = (Interest expense ÷ Principal balance) × 100. If the information came from the company's annual income statement, you're done.

To calculate an APR, lenders multiply the periodic interest rate by 365 days. Credit cards typically have a fixed APR, while some loans may have a variable APR.

The U.S. central bank’s decision to hold interest rates steady in June was unanimously supported, but officials were starting ...

Not all interest rates work the same. Your choice among these two main types come down to how you save and how you borrow. Here's what to know about fixed and variable rates.