A more thorough explanation:

Usurae centesimae is a Latin term that refers to the highest legal interest rate of 12% per year (1% per month). In ancient Rome, interest rates were calculated by dividing the principal sum into one hundred parts, with one part being payable monthly as interest.

For instance, if you borrow $1000 at a usurae centesimae rate of 12%, you will have to pay $120 in interest per year or $10 per month. Similarly, if you lend $5000 to someone at the same rate, you will earn $600 in interest per year or $50 per month.

Another example is when a bank charges a usurae centesimae rate of 12% on a credit card balance. If you have a balance of $5000, you will have to pay $600 in interest per year or $50 per month until you pay off the balance.

These examples illustrate how usurae centesimae works and how it affects borrowers and lenders. It is important to note that usurae centesimae is the highest legal interest rate allowed, and any rate above it is considered usury and is illegal.