Rounding error of floating-point arithmetic (rounding error)

When reading the rhino book, I suddenly found an interesting place to record: I

went to the browser and tried it and it turned out to be like this:

I tried c# again, which is also the case.

But there is a decimal data type in c#, and there is no loss of accuracy

this morning. I checked csdn, and I accidentally saw a similar article. Come over and see if the one I wrote before is correct. By the way, I will post the solution ideas of the boss, the original portal