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Message: [QUOTE="Joe User, post: 13711843"] I can explain the difference, but it can get very technical. I could probably explain things better if you provided the VBA example. But generally.... Both Excel and VBA (for type Double) store numbers using the IEEE 64-bit floating-point form. However, Intel-compatible CPUs use 80-bit floating-point registers to perform computations. The 80-bit FP form extends both the precision and the range of values. Excel stores the 80-bit result of each pairwise arithmetic operation into 64-bit variables, which causes a loss of precision. VBA tries to keep intermediate results in the 80-bit form. That does not always lead to differences in the result. Usually, that depends on the order and magnitude of the pairwise arithmetic operations. In summary, the expression Min/60/24 is evaluated by both Excel and VBA as x = Min/60, then x/24. Likewise, Min/24/60 is evaluated as x = Min/24, then x/60. Mathematically, there is no difference. But when the results of the pairwise operations cannot be represented exactly in a finite number of bits, the order of operations can make a small difference in the least-significant bits. Moreover, a difference can arise when Min/24 or Min/60 is converted from 80-bit FP to 64-bit FP, as Excel does. The operative word is "can"; sometimes there is no difference. I hope that helps. ----- original message ----- Thank you both for your replies. Joe - I've noticed the difference between Excel and VBA as well. I tried to reproduce an error present in some VBA code (subtracting times) but was unable to - there didn't seem to be any correlation between the two calculation methods (i.e. i couldn't discern a pattern between the numbers being subtracted and whether the rounding error was above or below, or if it was exact). [/QUOTE]

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