A mate just sent me this. I haven't a clue personally but one of you smart ones might
138 is the smallest three digit number whose digital sum is half digital product. find all three digit numbers with this property, and which are multiples of 5
For num = 100 To 999
digSum = 0
digProd = 1
For i=1 To Len(num)
dig = Mid(num,i,1)
digSum = digSum + dig
digProd = digProd * dig
Next
If (digProd = 2 * digSum) = True Then
If num Mod 5 = 0 Then
WScript.Echo num
End If
End If
Next
WScript.QuitYay!
Not quite as pretty....and i cheated slightly working out multiples of 5 
List<int> answers = new List<int>();
for (int i = 100; i < 1000; i++)
{
string first = i.ToString().Substring(0, 1);
string second = i.ToString().Substring(1, 1);
string third = i.ToString().Substring(2, 1);
int firstnum = int.Parse(first);
int secondnum = int.Parse(second);
int thirdnum = int.Parse(third);
if(thirdnum == 5 || thirdnum == 0)
{
if (((firstnum * secondnum * thirdnum)/2) == (firstnum + secondnum + thirdnum))
{
answers.Add(i);
}
}
}