Anyone can make a daft mistake with arithmetic, references and simple technical information.

The brain can look at a piece of writing which contains a glaring mistake and, missing it the first time, never see the error subsequently.

In 1999, the Hubble telescope's mirror was found to be incorrectly ground leading to an astigmatism. Someone wrote, or read, the specifications wrongly. The 1999 Mars Climate Orbiter was lost partly, but not wholly, due to a confusion between Britsh and American units.

There is no magic solution. Pass the premise of your calculations to someone else and see if they get the same answer.

We will look at arithmetic and engineering calculations for you to see if we can find an error.