问题如下：
The Grace Corp invested a project with the initial investment of $10,000. This project will generate cash inflows presented below:
Year 1: $5,000
Year 2: $4,000
Year 3: $3,000
Year 4: $2,000
What is the project's payback period assume the required rate of return is 10%?
选项：
A.2.0 years.
B.2.33 years.
C.2.95 years.
解释：
B is correct.
Payback period =2+1000/3000=2.33 years.
老师，如果这道题问的是DBP就应该选2.95对吧，如果算2.95的思路（论考试节约时间）就只需要算前两年和前三年的npv，我的问题是：按计算器的时候必须从头到尾分别按两次：前两年和前三年？（还是说有简便输入的方法？我每次算这种题都是得出一个数，清零，再按一次，得出另外一个数）
