Summary:

1. Mathematical Operators are +,-,*,/^ respectively addition, subtraction, multiplication, division and orders (aka powers, indices)
2. Mathematics dictates the Order of Operations that Excel implements, and if this is new to you, then there is simple way to remember the order - Calculate from left to right, and apply BODMAS (Brackets, Orders, Division, Multiplication, Addition, Subtraction - from left to right in this list is what the priority order of calculation is)
3. Use brackets to achieve any desired calculational result
4. Nesting brackets means the inner most nested set is calculated first - this applies to everything, including nesting functions as will be seen later