Select the cell with the formatting you want to copy
Click the Format Painter on the Home tab
Drag over the cells you want to apply the format to
Double-click Format Painter to apply the same format to multiple areas
Copy the cell with Ctrl+C
Select the target cells
Use Paste Special and choose Formats
Use Ctrl+Shift+C to copy formatting
Use Ctrl+Shift+V to paste formatting
Right-click the source cell and use Copy
Right-click the target cells and choose Paste Special, then Formats