I noticed a difference in the results of a math problem I did in 4 separate programs, and they split 2 to 2 on the result. I multiplied the following 2 numbers in Windows Calculator, a Firefox add-on calculator, Libre Office Calc and MS Excel with interesting resuts : 82.19777664*33.20088775 Results Windows Calculator = 2,729.039155524212 Firefox Add-on Calculator = 2729.039155524212 Libre Office Calc = 2,729.039155524210 Microsoft Excel 2010 = 2,729.039155524210 As you can see, the calculators agree on the numbers and the spreadsheet programs agree on the numbers, but as you can also see the 2 different types of programs agreed on different numbers - it appears the spreadsheets rounded the last number down to zero. I allowed for 12 decimal places in the spreadsheet programs, I even added decimal places to 14 or 15 and I got the same results - with additional trailing zero's in the additional decimal places in the spreadsheet programs. Anyone have any idea how and why these programs are handling the math this way? Thanks for any insight anyone can shed on this riddle

The answer you are looking for deals with numeric precision. Numeric precision in Microsoft Excel Floating-point arithmetic may give inaccurate results in Excel IEEE floating point - (look closely at the number of digits for each level of precision.)

An interesting bit of trivia arising out of this question - it is not many years since a pc asked to calculate 1/7 would give the output as 0.142857142857142 . . . . . (recurring ad inf). If the answer were then multplied by 7 it responded with 0.9999999 . . . . which is understandable. Combining the two stages into one however, 1/7*7 gave the same result 0.99999. . .!

That is a very interesting piece of trivia patcooke, I've already learned a couple of interesting facts from this post, thanks for that one

I'm retired and used to run a CNC machine and in a few instances the rounding caused some real frustration. The machine did it's thing and the prgram they used to create the machine's program did it's job and occasionally there was a puzzling fault that stopped the program. That and the machine's probe used 8 places and displayed values rounded back to 4 but calculated with the 8. My day man and I eventually things figured out and shared the info freely. The programers were pretty clueless! Joe