Agreed, although technically you only need to put one apostrophe (at the start). This is also useful when you want a formula to appear as text - eg '=1+2 would appear as =1+2 rather than 3.
If you don't want to edit an apostrophe into each cell, you can achieve the same thing by formatting the cells as text - right click on the highlighted cells, select Format Cells, then choose the 'Text' option from the category list.