Here, what kind of topic is compound interest, what kind of topic is it, and what things are said here? Understand now if we know here, then what is the difference between simple interest and compound interest? For example, if we are giving you $100 and giving it at the rate of 10%, then as per simple interest, the interest that will be calculated in the first year will also be on $100, the interest that will be calculated in the second year will be on $100, the interest that will be calculated in the third year will also be on $100, and the interest that will come every year will be fixed and it will be $10. But when we talk of compound interest, it means that in the first year, the interest we will get here is 10% of $100, that is, $10. Now, the interest in the first year will come to you, so what you will do here is add $10 to $100, and then it will become $110. Now your principal is no longer $100; it has become $110. The interest that will be calculated will be on top of $110. Then we will find out it is 10%, which is $11, and by doing this, the value will keep on adding; that is, compound interest means that you get interest on the principal as well as interest on the interest. So here, this value is much bigger than simple interest. We are go to calculate the entire compound interest in three ways, and these three methods are quite popular. First of all, if we talk about it here, the first method is the ratio method, and the second is the successive method. And the third is the tree method.