I noticed something while using Goal Seek the other day that peaked my
interest. Here's the scenario in which you can replicate my question.

In cell A1 enter: 5
In cell A2 enter: =A1
In cell A3 enter: =A1*A2

The result in cell A3 should equal 25.

Use Goal Seek to set cell A3 to 36 by changing cell A1. The result in
cell A3 is 35.99994, not 36 as you'd expect. Cells A1 and A2 both
contain 5.999995 instead of 6.

Can anyone explain why Excel does this? Thank you.