For example, it is not possible to enter text and numbers in the same cell, and then be able to use the number in a calculation. The entire contents of the cell would be treated as text.
Spreadsheets are widely used because they allow you to use formulas to perform repetitive calculations. Formulas use cell names to perform calculations.
Answer to formulas will change when values in the cells it refers to change. This makes a spreadsheet dynamic and powerful.