求VB编程

来源：百度知道 编辑：UC知道 时间：2024/05/12 20:36:54
编写程序：
* 有一分数序列：2/1，3/2，5/3，8/5，13/8，21/13...，求出这个数列的前20项之和。
* 运算结果取小数点后两位

楼上错解。

Dim a As Integer, b As Integer
a = 1
b = 1
For i = 1 To 20
b = a + b
a = b - a
Sum = Sum + b / a
Next
MsgBox Round(Sum, 2)

从这个数列可以看出.
后一个数等于前两个数的分子和,和分母和.
2 3 5 8
- - - - ....
1 2 3 5

Dim a(21) As Integer, b(21) As Integer, i As Integer
Dim sum As Single
sum = 0
b(0) = 0
a(1) = 2
b(1) = 1
For i = 1 To 20
sum = sum + a(i) / b(i)
a(i + 1) = a(i) + b(i)
b(i + 1) = b(i - 1) + b(i)
Next i
Print FormatNumber(sum, 2)