Hi,

The "Floating point" has been extensively discussed in this ng and I
understand why it causes errors. But I haven't found an "efficient" way to
deal with a simple thing like:
If cell-value = 1 Then 'blah

Sub test2()

[a1] = 0
[a2].Formula = "=A1+0.05"
[a2].AutoFill [A2:A21]
Debug.Print "[a21]=1", [a21] = 1 'False
Debug.Print 1 - [a21] '-2.22044604925031E-16

Dim nDouble As Double, nSingle As Single
nDouble = [a21]: nSingle = [a21]
Debug.Print "nDouble=1 ", nDouble = 1 'False
Debug.Print "nSingle=1 ", nSingle = 1 'True

'Single fixes above but causes problems later
nDouble = WorksheetFunction.Round(nDouble / 10, 2)
nSingle = WorksheetFunction.Round(nSingle / 10, 2)
Debug.Print " 'divide by 10 and round"
Debug.Print "nDouble"; nDouble, "nSingle"; nSingle
[c1] = nDouble
[c2] = nSingle
Debug.Print "[c1]=0.1", [c1] = 0.1
Debug.Print "[c2]=0.1", [c2] = 0.1, [c2] - 0.1
End Sub

Coercing to a Single appears to resolve my problem, but causes yet further
rounding problems downstream.

Of course could test with a Single then work with a Double. But this seems
like a lot of overhead in a long loop, and even more so in a UDF. Also could
use Round or in xl97 Worksheetfunction.round, but the latter in particular
is slow. Or maybe check within range +/- 1E-14.

Various alternative solutions have been suggested and Tom Ogilvy posted a
useful set of links he
http://tinyurl.com/662oo

However I would be grateful for advice as to the fastest / most efficient
way to ignore [say] the 14th decimal in a cell value.

TIA,
Peter T