I've written a function in VBA that requires the Base-10 Log of a
number to be rounded DOWN to the closest integer. E.G. 10.1 would be 1.
10.9 would be 1, etc.

What I'm finding in VBA (whether I run this from Excel, Access, etc) is
that when x (below) is a power of 10, the result is wrong. In this
snippet, z SHOULD evaluate to 1 (i.e., log-base10(10)=1, int(1) = 1).
But it's not working that way. The last line shows why. The variable y
is evaluating to a number *just below* - 1-y is 1.11022E-16.

Anyone ever seen this, or know a good workaround. The function really
depends on this working correctly.

TIA!

Sub test()
x = 10
'Return Log base 10 of x,
' 1 in this case
y = Log(x) / Log(10)
'Round y DOWN to the nearest
' integer. Should be ONE
' in this case
z = Int(y)
Debug.Print z
Debug.Print Format(1 - y, "#.#####E-###")
End Sub