Money can grow if you \"plant\" it in the right places—places like savings accounts¹ at banks.If you leave your money in one of these places for a long time， it can grow into a much larger amount. The reason for this is something called compound² interest.

Let's say that when you were born， your grandpar- ents put $1，000 into a bank account to save for your college education.When they put the money in the bank， the bank agreed to pay 10 percent each year for every year they left the money there. (Ten percent is actually higher than what most banks would pay these days， but it makes the math³ easier if we use that figure.) This 10 percent is called \"interest.\" The bank could pay the interest in two ways，one called\"simple\"and the other called \"compound.\" Let's start with simple interest because it is simpler!

In figuring out simple interest， the bank would take 10 percent of $1，000， or $100， and add it to your grandparents' account each year. If your grandparents left the $1，000 in the account until you reached 18 years of age， the bank would pay $1，800 in simple interest. Add that amount to the original $1，000 deposit⁴， and by the time you were ready for college， you would have $2，800.

Compound interest is different. Year after year， it is based on a bigger and bigger amount. Here's how the bank would figure compound interest on your grandparents' account. In the first year， the bank would pay $100， or 10 percent on the original $1，000，the same as if it were paying simple interest. At the end of the second year， the bank would combine， or \"compound，\" the first year's interest of $100 with the original $1，000. As a result， they would figure the interest based on 10 percent of $1，100， not $1，000. The bank would add the $110 to the $1，100 already in the account for a total of $1，210 after the second year.

The bank would do this year after year， figuring each year's 10 percent interest payment not on the original $1，000，but on $1，000 plus all of the previous⁵ years' interest payments. If the bank kept doing this for 18 years， your grandparents would have about $5，560—more than five times what they started with!

When you are saving money， compound interest can make your money grow into a really big amount. The longer you leave your money in savings， the bigger it will grow. If you wait long enough， the moneyyou \"plant\" will grow into a great big money tree.

1．a(chǎn)ccountn．帳戶

2．compound adj．復合的~interest復利

3．mathn．[美口]=mathematics 數(shù)學運算，數(shù)學應用

4．deposit n.存款

5．previousadj．以前的，前的，先前的

如果你在合適的地方“播種”錢，錢就能增長——銀行儲蓄賬戶就是那樣一種地方。如果你把錢在這類地方放很長時間，它就能增長為很大的數(shù)額。其中的奧妙就是“復利”的作用。

假設你出生的時候，祖父母為你的大學教育往銀行賬戶存了1000美元。當他們把錢存入銀行，銀行同意為他們存在銀行的錢每年支付10％的利息。(10％實際上比現(xiàn)在大多數(shù)銀行愿意支付的利息高，但是為了計算方便我們就采用這個數(shù)值。)這 10％就叫“利息”。銀行付利息有兩種方式，一種叫“單利”，另一種叫“復利”。現(xiàn)在讓我們從單利開始說起，因為它比較簡單。

在計算單利的時候，銀行會把1000美元的10％即 100美元，每年加入你祖父母的賬戶。如果你的祖父母在賬戶中存了1000美元，到你18歲的時候銀行將按照單利付給你1800美元。加上原來的1000美元存款，你上大學的時候?qū)⒂?800美元。

復利就不同了。它是基于年復一年越來越大的數(shù)額計算出來的。下面就講講銀行是怎么對你祖父母的賬戶進行復利計算的。第一年，銀行付給100美元即本金1000美元的10％，就像按照單利支付那樣。第二年末，銀行會把第一年的利息100美元和本金1000美元加起來做為基數(shù)。因此他們會按照 1100美元的10％計算利息，而不是1000美元。第二年后，銀行會在賬戶中已有的1100美元上加上110美元，合計達到1210美元。

銀行會年復一年地按照這個辦法計算每年支付的利息，不是以本金1000美元為基礎，而是以1000美元加上此前每年支付的利息總數(shù)為基礎。如果銀行連續(xù) 18年這樣做。你祖父母就有了5560美元——是開始時的5倍多!

當你存錢的時候，“復利”能使你的錢增長到很大的數(shù)額。存的時間越長，增長的越多。如果你等待的時間足夠長，你“種”的錢將長成一棵巨大的“錢樹”。