In the graphic below, was the number 80 in this cell typed in or the result of a formula? How can you tell? Look at the formula bar contents to see how the number 80 was generated. Does it have an 80 in it? If so, the number was typed into that cell. If all you see is a formula, the number 80 is the result of the formula you’re viewing.
Which brings us to our second point about entering formulas into a cell:
If a formula is entered in a cell and you press the enter key, the only data you will see in that cell is the result of the formula, not the formula itself. The formula will be seen only in the formula bar (FIGURE 1).
Steps to Entering a Formula:
 To enter any formula, you must always begin by entering the equals symbol =
 Enter the formula name. For example, if you wanted to sum (add) three numbers of a range or table, you would enter SUM or sum; you can use upper or lower case.
 Enter the open parenthesis symbol (
 Enter the beginning cell address of the range of data to be summed. If the first address to be summed is cell address A1, then you would enter A1.
 Enter a colon :
 Enter the ending cell address of the range or table to be summed. If the ending address to be summed is cell address A3, then you would enter A3
 Enter the closed parenthesis symbol )
 Press the enter key to execute the formula.
 The result of performing steps 1 through 7 are shown below in FIGURES 4 and 5. FIGURE 4 shows what it looks like before Step 8; FIGURE 5 shows what it looks like after Step 8.
MOUSE METHOD: You can also perform steps 4, 5, and 6 automatically by selecting the first cell address in the range with your mouse, then drag the mouse to the last cell address in the range. Excel will automatically insert a colon between the cell addresses selected.
Remember: The result of any formula always appears in the cell after the enter key is pressed and the formula disappears from the cell. The formula can only be seen by looking at the formula bar contents.
FIGURE 4 (Before pressing the Enter key)

FIGURE 5 (After pressing the Enter key)

STEP 1: (FIGURE 6) We are going to create a table of data and total it using the formula SUM.
Starting with cell address A1, enter the following data as shown in FIGURE 6. Remember cell alignment rules: After entering text, the text will be leftaligned in the cell; numbers will be rightaligned in the cell. 
FIGURE 6

STEP 2A: (FIGURE 7) Make cell B5 the active cell.
STEP 2B: (FIGURE 7) Enter the following into cell B5: =SUM( THERE ARE 2 WAYS TO SELECT CELLS TO BE SUMMED: OPTION 1: STEP 2C: (FIGURE 7) Use the mouse to select the data to be summed. Move mouse to B2, click and drag mouse down through B4 (FIGURE 7). OPTION 2: STEP 2F: (FIGURE 8) Press Enter. James total will be in cell B5. James total should be 68. SUMMING NONADJACENT CELLS Exercise 8 continues in Section 4.4.1 
FIGURE 7
FIGURE 8
FIGURE 9
