中文：

利息积数是指在一定时期内，按照约定的利率计息，每期应计利息的累积总和。它是一种简单而有效的计息方法，尤其适用于计算较大金额的利息。

在计算利息积数时，需要先确定几个关键因素：计息期限、利率和本金。计息期限是指从开始计息到计算结束的时间长度；利率是指每期应计的利息与本金的比例；本金是指需要计算利息的原始资金。

利息积数的计算公式为：利息积数 = 本金 × 计息期限 × 利率。这个公式可以用来计算在一定期限内，按照约定利率应计的利息总和。

与简单利息不同，利息积数考虑了每期应计利息的累积效应。这意味着在每期计息时，之前各期的利息也会得到累计计算，从而得到更精确的利息结果。

英文：

Interest product is the cumulative sum of interest that should be calculated in each period according to the agreed interest rate within a certain period of time. It is a simple and effective way of calculating interest, especially suitable for calculating the interest of larger sums of money.

When calculating the interest product, several key factors need to be determined: the period of interest, the interest rate, and the principal. The period of interest refers to the length of time from the beginning of interest calculation to the end of calculation; the interest rate refers to the proportion of interest to principal that should be calculated in each period; and the principal refers to the original funds that need to be calculated for interest.

The calculation formula for interest product is: interest product = principal × period of interest × interest rate. This formula can be used to calculate the total amount of interest that should be calculated according to the agreed interest rate within a certain period of time.

Unlike simple interest, interest product considers the cumulative effect of each period's interest calculation. This means that when calculating interest in each period, the accumulated effect of interest from previous periods is also considered, resulting in more accurate interest results.