Question

VB 求前N项和 急

求下面数列所得前N项和保留4位小数 数列是1/（1+2）1/（1+2+3）1/（1+2+3+4）
求下面数列所得的得数保留4位小数数列是1/（1+2）1/（1+2+3）1/（1+2+3+4）后面以此类推

Answer 1

Function sum(ByVal n As Integer) As String
    
    Dim i As Integer
    Dim a As Double
    Dim b As Integer
    b = 1
    If n < 2 Then
        
        sum = 1
        Exit Function
    End If
    For i = 2 To n
        
        b = b + i
        a = a + CDbl(1 / b)
    Next i
    sum = Format(a, "#.0000")
End Function
Private Sub Command1_Click()
    
    MsgBox sum(6)
End Sub
参考这个，希望可以帮到你

Answer 2

Private Sub Command1_Click()
Dim n As Integer, i As Integer, mysum As Single, p As Single
n = Val(InputBox("请输入一个数："))
For i = 1 To n
mysum = mysum + i
p = Format((1 / (mysum + i + 1)), "0.0000")
Next i
MsgBox p
End Sub

Answer 3

function sum(num as integer)
sum=(1+num)*num/2
end function

private sub command1_click()
dim i as integer
dim s as double
s=0
for i=1 to n
s=s+1/sum(i+1)
next
msgbox round(s,4)
end sub

private sub command2_click()
dim i as integer
for i=1 to n
msgbox round(1/sum(i+1),4)
end sub

追问

这个是VB么，我不懂，帮别人问的。我打的/是分之哦

追答

是vb啊。