If you want to increase all numbers by 5%:
In an empty cell, enter the number 1.05
Edit>Copy
Select all your numbers
Edit>Paste special, check Multiply
--For example if you need to increase 10% enter 1.1 in a cell. Copy the cell
--Keeping the copy select the range of cells
--Right click>PasteSpecial>
--Select 'Multiply' and click OK.