Write a simple formula that starts with =

A formula is an instruction that tells Excel to calculate. Microsoft's formula pages repeat one rule: a formula always begins with an equal sign (=). If you type 2+4 without the equal sign, Excel usually treats it as text — it will not give you 6. If you type =2+4 and press Enter, Excel runs the calculation and the cell shows 6. The formula bar still shows =2+4, so you can see how the answer was made.

Microsoft's simple-formula page says a simple formula starts with =, then numbers (constants) and operators:

• + add
• - subtract
• * multiply (asterisk, not the letter x)
• / divide (forward slash)

Their starter examples are =2+4, =4-2, =2*4, and =4/2. You can type those on the Practice sheet right now. After you press Enter (Windows) or Return (Mac), the cell shows the result. Microsoft also notes that you can press Ctrl+Enter if you want the cursor to stay on the active cell after the formula calculates.

Type the equal sign first, then the rest. If you forget = and already pressed Enter, click the cell, type the formula again starting with =, and press Enter. Watch the formula bar, not only the grid, when you want to know whether a cell holds a formula or a typed-in number.

You can practise these tiny formulas on the Practice sheet without touching the sample Hours or Household data. Use a clear empty area, such as row 10 downward, so your tests do not sit on top of headers.

Adding =2+4 is a good first test, but everyday lists change. If Wednesday's hours change from 7.5 to 8, a formula that literally says =6+4+7.5 will be wrong until you edit it. A better habit is to point at the cells that already hold the numbers.

Microsoft's overview shows this pattern: select a cell, type =, select a cell (or type its address), type an operator, select the next cell, and press Enter. The result appears in the cell that holds the formula. Microsoft's simple-formula page adds that instead of typing the numbers, you can select the cells that contain the values and type the operators between those selections.

On the Hours sheet, click an empty cell such as E2 and type =B2+B3+B4, or type =, click B2, type +, click B3, type +, click B4, and press Enter. If the sample data is unchanged, the result is 17.5 (Monday 6 + Tuesday 4 + Wednesday 7.5). If you later change B4 from 7.5 to 8, this formula can update to 18.

Microsoft's overview also says it is generally best to put constants in their own cells and refer to those cells, rather than burying numbers inside a formula. That habit will matter even more in Lesson 7, when you copy a formula down a column.

If the result looks like a date or a long string of hash marks, the cell may be too narrow or formatted strangely. Click the cell, read the formula bar, and confirm the cell references before you change anything else.

Excel follows the standard order of mathematical operations. Microsoft's simple-formula page states that multiplication and division are performed before addition and subtraction. Their example is to type =5+2*3 and press Enter. Excel multiplies the last two numbers (2 × 3 = 6) and then adds the first number (5 + 6). The result is 11, not 21.

This matters in real lists. Suppose you want to add two hour totals and then multiply by a sample extra rate later in the course. If you write the operators in a long line, Excel will not always go left to right. Read the formula bar and do a rough check in your head: “Which part happens first?” If the on-screen answer is far from your estimate, look at the operators before you trust the cell.

This course stays with the four everyday operators Microsoft teaches for simple formulas: add, subtract, multiply, and divide. You do not need more advanced operators to finish the practice workbook. What you do need is the habit of starting with =, pointing at cells when the numbers already live on the sheet, and checking that 11-versus-21 kind of surprise.

If a formula shows an error such as #DIV/0!, you may have divided by a cell that is empty or zero. Click the formula cell, read the formula bar, and fix the cell references rather than typing over the result with a guessed number. The displayed result should come from the formula.

1. On the Practice sheet, type =2+4 and confirm you see 6.
2. On the Hours sheet, in E2 type =B2+B3+B4 (by typing or by clicking the cells) and confirm 17.5.
3. In another Practice cell, type =5+2*3 and confirm 11.
4. Click each formula cell and read the formula bar so you see the instruction, not only the result.

When would you rather click cells to build a formula than type addresses such as B2? When might typing the address be easier?