九、  埃及分数：
古埃及人有一个非常奇特的习惯，他们喜欢把一个分数表示为若干个分子为 1 ，分母不同的分数的和的形式。例如： 7/8=1/2+1/3+1/24 
答：
源程序：
Private Sub Command1_Click()
Dim a As Long, b As Long, i As Long
Dim g As Long, t As Long
Dim s As String
s = ""
i = 2
a = Int(Trim(Text1.Text))
b = Int(Trim(Text2.Text))
t = gcd(a, b)
a = a \ t
b = b \ t
Do
    If a > b Then
        s = s & "1/1+"
        a = a - b
    Else
        If a / b >= 1 / i Then
            g = i * b \ gcd(i, b)
            a = a * (g \ b) - g \ i
            b = g
            t = gcd(a, b)
            a = a \ t
            b = b \ t
            s = s & "1/" & i & "+"
            If a = 1 Then
                s = s & "1/" & b
                Exit Do
            End If
        End If
        i = i + 1
    End If
Loop Until (a = 0)
If Right(s, 1) = "+" Then s = Left(s, Len(s) - 1)
Text3 = s
End Sub
Private Function gcd(ByVal x As Long, ByVal y As Long) As Long
Dim t As Long
Do
    t = x Mod y
    x = y
    y = t
Loop Until (t = 0)
gcd = x
End Function
Private Sub Command2_Click()
Text1.Text = ""
Text2.Text = ""
Text3.Text = ""
Text1.SetFocus
End Sub

Private Sub Command3_Click()
End
End Sub

Private Sub Text1_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
    Text2.SetFocus
End If
End Sub

十、用1—9这9个数组成三个三位的平方数，要求每个数字只准使用一次。
答：

源程序：
Private Sub Command1_Click()
Dim i As Integer, j As Integer, k As Integer, t As Integer
Dim a() As Integer, b(1 To 9) As Integer
Dim s As String
For i = 1 To 9
    b(i) = i
Next i
l = 0
s = ""
For i = 1 To 9
    b(i) = i
Next i
For i = 1 To 9
    For j = 1 To 9
        For k = 1 To 9
            If i <> j And i <> k And j <> k Then
                 t = b(i) * 100 + b(j) * 10 + b(k)
                 If pfs(t) And Len(CStr(t)) = 3 And Right(CStr(t), 1) <> "0" Then
                    l = l + 1
                    ReDim Preserve a(l)
                    a(l) = t
                End If
            End If
        Next k
    Next j
Next i

For i = 1 To UBound(a) - 2
    For j = i + 1 To UBound(a) - 2
        For k = j + 1 To UBound(a)
            s = a(i) & a(j) & a(k)
            If pd(s) = True Then Text1 = a(i) & "  " & a(j) & "  " & a(k)
        Next k
    Next j
Next i

End Sub
Private Function pd(s As String) As Boolean
Dim i As Integer
For i = 1 To Len(s) - 1
    For j = i + 1 To Len(s)
        If Mid(s, i, 1) = Mid(s, j, 1) Then
            pd = False
            Exit Function
        Else
            pd = True
        End If
    Next j
Next i
   
End Function
Private Function pfs(t As Integer) As Boolean
If Int(Sqr(t)) ^ 2 = t Then
    pfs = True
Else
    pfs = False
End If
End Function