The following case is a simple, straightforward question, where we already know the answer, and we’re just going to see if Excel can come up with the same answer we do. In cell A1, I have the words First Day, and in A2, the words Second Day. These are merely a point of reference, nothing more.
In B3, we’re going to ask Excel to add up the numbers in B1 and B2, which are 1 and 2, respectively. Fortunately, even people like me, who majored in English in a vain and misguided attempt to avoid math, could answer this question without a calculator. When we’re first getting our Excel sea legs under us, this ability to know the answer already comes in handy.
The way to make this happen is to use the AutoSum button, which is located on the far right side of the Home tab:
When I click that button, the screen now looks like this:
In essence, Excel is asking you a question – “Do you see these numbers that I have selected? Are these the numbers you want me to add up?” The nomenclature goes like this – SUM is the function that Excel is performing upon the cells in question. The first cell is B1, and the last cell is B2; the colon (:) between the two indicates “through”; that is to say, “Sum up all the numbers from cells B1 through B2.” The last cell could be B3, B4, B1048756, it matters not.
Of course, when we press Enter to accept Excel’s idea, we get 3. That’s unsurprising. The good news is, if we change the 1 in cell B1 to be a 2, the total will automatically update to 4.[2] Of course, the next question that raises is, how do we insert new rows, and have the total automatically update? I may have to add a new day, or another line item, and I don’t want to have to re-do the total.
The simple answer is, “insert the row in the middle.” In this case, that means inserting the new row between rows 1 and 2. 1 is the first row, so we don’t want to insert above that; 2 is the last row, so we don’t want to insert below that. If we inserted our new row in either one of those places, then Excel gets confused.
To select row 2, click the number 2:
Then, with your mouse held over that number 2, right-click and choose Insert:
You now have a new row, between rows 1 and 2.
In the new A2, I wrote the words Third Day, and then wrote the number 2 in cell B2.
The moment I press Enter, the total changed. (Blink and you miss it!)