Currency
The term currency might be a synonym for the $ and 2-decimal places. Much of the arithmetic found in spreadsheets concerns money and Excel developers like to be able to display their work with the proper format.
The process for formating a number as money starts out like the other number formats. You begin by selecting Format + Cells.
When the Format Panel options appears, you would select Number and then Currency.
Note the default settings give you the 2 Decimal places and the $ symbol.
While you are viewing this panel, note there are some other settings you could do to format the number(s) selected from the financial perspective.
The results of selecting the format of Currency will look like the following example:
Before Formatting After Formatting 12.4 $12.40 3.233 $3.23 4.238$4.24
23 $23.00