Cycles through four number formats for all selected cells:
General, Number, Currency, Date, Percentage.
You can optionally change this cycler to include up to 10 user defined formats by setting the ‘Custom Keys/Cycles’.
Let us say column C has numbers that are dollar amounts. To change all of column C’s cells to the currency format, merely select all of column C (or just the range you prefer) and then with your left hand hold down Ctrl + Alt + Shift. While still holding those buttons down, use your right hand to hit Backspace as many times as needed to cycle through to the currency format.