There are two primary shortcuts for using the SUM function in Excel, both designed to save you time and effort:

1. Keyboard Shortcut (Alt+)

This is likely the fastest and most widely used method. Here's how it works:

* Position your cursor: Move your cursor to the cell where you want the sum to appear.
* Press Alt + =: Hold down the Alt key on your keyboard and then press the = (equals) sign. This is a one-step shortcut that activates the AutoSum function.
* Excel guesses the range: Excel will intelligently analyze the surrounding cells and attempt to select the most likely range to be summed. In most cases, it will highlight the column or row above the cursor, assuming you want to total the values in that direction.

Pros:

* Extremely quick for simple sums.
* No need to click around with the mouse to select a range.

Cons:

* May not always guess the correct range, especially when working with complex data layouts.
* Requires you to potentially adjust the selection if Excel doesn't pick the right range.

2. Formula Bar Shortcut (SUM( with dropdown)

This shortcut leverages the formula bar and Excel's auto-complete features for a more guided approach:

* Click on the target cell: Select the cell where you want the summed value displayed.
* Start typing =SUM( in the formula bar: The formula bar is located directly above the spreadsheet. Begin typing the formula `=SUM(`, which is the standard way to initiate a SUM function.
* Dropdown suggestion: As soon as you type the opening parenthesis after SUM, Excel will likely present a dropdown menu suggesting the most likely range to sum. This range is based on your cursor's position.

* Two options:
* Accept the suggestion: If the highlighted range is correct, simply press Enter to complete the formula and calculate the sum.
* Adjust the range: If the suggested range is incorrect, you can directly modify it within the formula bar before pressing Enter. Use the arrow keys or your mouse to expand or contract the selection.

Pros:

* Provides a visual confirmation of the range being summed.
* Offers the chance to adjust the range before finalizing the formula.

Cons:

* Slightly slower than the Alt+ = shortcut as it requires some typing.
* May not always provide the perfect range suggestion, requiring manual correction.

Ultimately, the best shortcut for you depends on your personal preference and how comfortable you are with formula editing. Both methods offer a significant advantage over manually selecting cells and typing the entire formula.