Formulas
It is an arithmetic expression contains operands and operators.

Formula must start with = sign

Eg:
=2+3 is formula
+ is operator
2,3 are operands

Operands can be numbers, cell Addresses

Eg:
=A1+4
=A2+B4

The benefit of using cell address instead of number is result of the formula would update when you modify the source data.

The result of the formula appear inside cell and formula can be seen through formula bar or in editing mode of cell.

Show/hide formula in working view of the sheet: Ctrl+~ (tild)

Operators can be used in the formula:
Arithmetic Operators:
+ for addition
– for subtraction
* for multiplication
/ for division

Comparison Operators:
> greater than
>= greater than or equal to
< less than
<= less than or equal to
= equal to
<> not equal to

The result of the expression that contains Comparison operators would be True or False

Eg:
5>7
A6<25
B9=C8

the evaluation of Operators in the formula follows BODMAS rule
B – Brackets
O – Order
DM – Div and Mul
AS – Add and Sub