Alt key shortcut
By Neale Blackwood
Keyboard shortcut for the SUM function. If you prefer to use keyboard shortcuts to the mouse, then you can use a keyboard shortcut to mimic clicking the AutoSum toolbar icon. This can be helpful if you are on a laptop with an external mouse.
To insert the SUM function in a cell hold the Alt key and press the = sign. This will insert the SUM function with an estimated range within the brackets. There are two Alt keys on a standard keyboard. One on either side of the space bar.