Stop in for a cup of coffee
The whole equation discussion makes me laugh. It's only about how the equation is entered (written) into each OS that gives a different answer in each. The real question is what is the equation trying to solve for, then you can determine how to enter it into each OS to get a correct answer (excel would require an even different equation structure).
Note that the equation is entered into the phone and the calculator slightly differently. There is an extra space in the one on the calculator causing the OS to interpret the terms differently.