I believe that because the units for the program is in inches, the conversion to metric is a factor, perhaps rounding by an interger like 2 will give the result you are after

That’s a typical example of finite-precision computer arithmetic. The value 1.8 has no exact representation in binary. 1.799999999… is as close as the computer can get. So unless the value is rounded for display, you will see all those trailing 9’s. However, they signify nothing unusual.