求大佬解答，万分感谢，第五题的代码怎么弄呀

前面应该判断是不是数字，是不是整数
Public Function calcStepSum(ByVal m As Long) As Long
If m Mod 2 = 0 Then
Return (m / 2) * m + (m / 2)
Else
Return ((m - 1) / 2) * m + m
End If
End Function

2个求和的for循环

Option Explicit
Private Sub Command1_Click()
Dim m As Long, n As Long
m = InputBox("m的值")
n = InputBox("n的值")
Text1.Text = Round(CSng(求和(m)) / CSng(求和(n)), 3)
End Sub
Function 求和(a As Long) As Long
Dim i As Long, b As Long
b = 1
For i = 2 To a
b = b + i
Next
求和 = b
End Function

请教结业证换毕业证的问题，我医学院的现在大五实习了，现在还有3门不及格，请问还可以再学一年三门通过拿毕业证吗？

Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
Dim m As Integer
Dim n As Integer
Dim y As Single
m = InputBox("请输入m值：")
n = InputBox("请输入n值：")
y = cal(Val(m), Val(n))
TextBox1.Text = Format(y, "0.000")
End Sub
Private Function cal(ByVal a As Integer, ByVal b As Integer) As Single
Dim i As Integer
Dim j As Integer
Dim m1 As Integer = 0
Dim n1 As Integer = 0
For i = 1 To a
m1 = m1 + i
Next
For j = 1 To b
n1 = n1 + j
Next
Return m1 / n1
End Function