To duplicate a value from a cell you can use one of the below options:

• Click on the desired cell you want to duplicate to select it, hold the drop down rectangle then drag and drop down/up as many cells as you need to fill in.
• Select the cell you want to duplicate as well as all the down/upper cells you want to fill in, right click and from the contextual menu select Fill Down.
• Select the cell you want to duplicate as well as all the down/upper cells you want to fill in, go to menu Task – Fill and click the Fill Up or Fill Down.