Since you use "precision as displayed" not just the "mathematical" results
count, but also the formatting.
If I reproduce you case without that setting and with no explicit
formatting, both formulas generate "Error".

--
Kind regards,

Niek Otten
Microsoft MVP - Excel

"Bob" wrote in message
...
I created a spreadsheet using Excel 2003.
Error is displayed in cell F7 mistakenly, and it is not displayed in
cell F9.
The formulas used in those two cells (F7 vs F9) are mathematically
equivalent.
Can anyone figure out why it happens?

Thanks.

column B column C column D column E column F
Group Actual Purity Adjusted Total Adjusted
Weight Weight Weight
row 4 1 140.60 99.90% 140.46 140.460000
row 5 2 8.05 99.90% 8.04 148.500000

row 7 Check 1 (Display Error if E5 148.5 - E4) Error

row 9 Check 2 (Display Error if E4 + E5 148.5)

Note: "Precision as Displayed" in
Tools/Options/Calculation is checked.
formula in E4: =C4*D4
formula in E5: =C5*D5
formula in F4: =E4
formula in F5: =E4+E5
formula in F7: =IF(E5148.5-E4,"Error", " ")
formula in F9: =IF(E4+E5148.5,"Error", " ")