Why does Excel not round according to 8-byte IEEE 754

Question

The following expression evaluates to false in C#:

(1 + 1 + 0.85) / 3 <= 0.95

And I suppose it does so in most other progra

Answer 1

The article that you linked to is explicit about doing something nonstandard with values near 0:

Example when a value reaches zero 1.In Excel 95 or earlier, enter the following into a new workbook: A1: =1.333+1.225-1.333-1.225

2.Right-click cell A1, and then click Format Cells. On the Number tab, click Scientific under Category. Set the Decimal places to 15. Instead of displaying 0, Excel 95 displays -2.22044604925031E-16.

Excel 97, however, introduced an optimization that attempts to correct for this problem. Should an addition or subtraction operation result in a value at or very close to zero, Excel 97 and later will compensate for any error introduced as a result of converting an operand to and from binary.

The unspecified "optimization that attempts to correct for this problem" does mean that caution should be used in using Excel for numerical computations when strict agreement with IEEE 754 is required. Perhaps using VBA (which is unlikely to have this "optimization"?) might be a workaround.