Use Microsoft Excel’s "Paste Special" 

Have you ever been working in Excel and wanted to increase a list of values (perhaps a price list) by e.g. 10%?  You could achieve this by typing in the new values, or it can be done with a hidden column and formulas, or by making the cells all formula-based to start with when you create the worksheet.

A much easier way is to use PasteSpecial from the Edit Menu.

Open your worksheet, find an empty cell, type in your multiplier.  Remember, if you're looking to increase the values by 10% (for example), you'll want to type in 1.1 - 110%.  If you're looking to decrease values, it'll be under 1.00, e.g. reduce by 10% - 0.9.  Copy that cell - just highlight it and press CTRL-C or select Edit > Copy. 

Next, highlight the entire range of cells you want to update.  Select Edit > Paste Special.  You will now see a dialog box that lets you do a number of things.  In this case, you want to multiply.  Select that option under Operation, and then click OK. 

Microsoft Excel will apply the update and you'll be all set, without modifying the range of numbers by hand.  Interestingly, if you do this operation against a cell range with formulas, Excel will still do the update- in fact updating the formulas to include the multiplier you pasted in the operation.

Now simply tidy up the sheet by deleting the multiplier.

Convert Text Numbers to Real Numbers

Another little known use of this method is to quickly convert a range of cells where numbers have been stored as text. The majority of cases that involve numbers stored as text in an Excel sheet is from data that has been imported into Excel from another Application or Database. Since Excel 2002, these cells can be seen easily by a small green triangle in the corner of the cells. By clicking this you can see the error and choose to convert to numbers.

In earlier versions you can see this that the numbers are stored as text because they are by default aligned to the left (numbers align right unless you’ve manually changed that), and because in the formula bar you can see the apostrophe! This is an easy thing to overlook, since the apostrophe does not show up in the cell (it is only a text designation and not a true character being stored in the cell).

Once again, PasteSpecial will solve this problem.

1. Copy a Blank Cell (or a cell containing the number 0)
2. Select your list of text-numbers
3. Choose Paste Special from the Edit menu.
4. Paste=Values, Operation=Add

You could also multiply by 1; this will achieve the same result and not alter the number.

This works by forcing Microsoft Excel to understand that these are numbers. So using the numbers in a calculation does that.