In LibreOffice Calc and Microsoft Excel, you can perform basic calculations such as addition, subtraction, multiplication, and division directly in cells using formulas. Here’s a quick guide on how to use these operations.

 1. Addition (`+`)
   - Formula: `=A1 + B1`
   - Example: If A1 contains `10` and B1 contains `5`, then:
     =A1 + B1
     
     Result would be: `15`