If you work with several worksheets in your workbook, you can access data from the various worksheets by linking cells. This saves time, because you don't need to enter the values manually.
Here's how
1. Select the cell you shall retrieve data to.
2. Enter: =<Worksheetname>!<Cellname> (Worksheetname is the name of the worksheet you will retrieve data from and cellname is the name of the cell you shall retrieve data from).
Example: =Sheet3!D4
3. Press Enter