A more thorough explanation:

Block interest refers to a type of interest that is calculated and added to the principal amount of a loan. This is also known as add-on interest. For example, if you borrow $1000 with a block interest rate of 10%, you will have to pay back $1100 at the end of the loan term.

This type of interest is different from compound interest, where the interest is calculated on the principal amount as well as the accumulated interest. Block interest is a fixed amount that is added to the principal, regardless of how much you have already paid back.

Block interest is commonly used in short-term loans, such as payday loans or cash advances. It is important to understand the terms and conditions of a loan before agreeing to it, as block interest can make the loan more expensive than it initially appears.

For example, if you take out a $500 payday loan with a block interest rate of 20%, you will have to pay back $600 at the end of the loan term. This means that the cost of borrowing $500 for a short period of time is $100, which is a high cost compared to other types of loans.