Odd Excel calculation

[tstout1000]

I have a simple question that I cannot seem to answer. I am subtracting two numbers (calculated from two different methods). The numbers visually look identical even all the way down to the 30th decimal point; however, when I subtract them they show a difference at the 8th decical place. I cannot explain why. Can anyone else tell me what is going on?

 

[Joe4]

Yep, the famous floating point arithmetic issue, as explained here: Floating-point arithmetic may give inaccurate result in Excel - Office
Easiest thing to do is to add the ROUND function to your formulas, as shown in Method 1 of that link.