Create a Formula
While functions are very handy the developers of this program cannot anticipate everything you might want to do. They therefore expect you to be able to develop your own formulas as and when you need them. As long as you are aware of the available formula operators this is simpler to do than it sounds. Here are the principal operators:

In the cell where you want the answer to appear construct your formula starting with an = symbol. Your formula can be  quite sophisticated including a number of operators in one formula. If you do mix your operators, you need to use ‘BODMAS’ to ensure your calculation is accurate: