Workbook, sheets and cells
An Excel file is called a workbook (extension .xlsx). It contains one or more sheets, shown as tabs at the bottom of the window. Double-click a tab to rename it: a meaningful name (Achats, Ventes 2026) beats Sheet1.
Each sheet is a grid. The columns carry letters (A, B, C…) and the rows carry numbers (1, 2, 3…). Where they cross is a cell, identified by its column then its row: B3 is the cell in column B, row 3. A rectangular group of cells is a range: A1:E11 designates the whole rectangle between A1 and E11. The address of the active cell appears in the Name Box, to the left of the formula bar.
A few useful moves: Ctrl + arrow jumps to the end of a block of data, Ctrl + Home goes back to A1, Ctrl + Shift + arrow selects up to the end of the block.
Entering text, numbers and dates
Excel interprets what you type:
Ramette papieris text, left-aligned;4,5is a number (with the comma as the decimal separator in a French version), right-aligned;06/01/2026is a date, also right-aligned.
This default alignment is a valuable clue. An amount that is left-aligned, often with a small green triangle, is a number stored as text: it will not be added correctly. This happens with exports from accounting software, or with numbers typed with a period (4.5) instead of a comma. The warning button that appears offers Convert to Number.
A date is actually a number: the number of days elapsed since January 1, 1900. January 6, 2026 is 46028. That is what lets you calculate the gap between two dates with a simple subtraction. If a date suddenly shows up as a large number, only its format has changed.
Number formats
The format decides the display. You apply it with Home > Number or with Ctrl+1 (the Format Cells dialog):
| Format | Value entered | Display |
|---|---|---|
| General | 4,5 | 4,5 |
| Number, 2 decimals, thousands separator | 1234,5 | 1 234,50 |
| Currency (€) | 4,5 | 4,50 € |
| Short date | 06/01/2026 | 06/01/2026 |
| Long date | 06/01/2026 | mardi 6 janvier 2026 (Tuesday, January 6, 2026) |
| Percentage | 0,2 | 20 % |
The golden rule: the format never changes the value. A cell containing 0,333333 and formatted with two decimals displays 0,33, but it is 0,333333 that goes into the calculations. This is the cause of many “one-cent discrepancies” in accounting tables. To really change the value, you need a rounding function, which you will see later.
Presenting a readable table
- Make the header row bold and adjust the column widths by double-clicking the border between two column letters.
#####in a cell simply means the column is too narrow to display the number.- View > Freeze Panes > Freeze Top Row keeps the headers visible as you scroll.
- Avoid merged cells in a data table: they complicate sorting, filtering and PivotTables.
The status bar, your instant calculator
Select a range of numbers: the status bar, at the bottom of the window, immediately shows their Average, Count and Sum. Right-clicking the status bar lets you add the minimum and maximum. It is the fastest way to check a total without writing anything in the sheet, for example to verify that an export contains the expected amount.
Exercises
Solutions and tests stay on the server. In the student space, your code is run and checked, and the tutor gives hints before the solution.
Format a purchase list
Create the file
C:\Formation\fournitures.csvwith Notepad, paste in the content below, save it, then open it in Excel by double-clicking it. The data occupies the rangeA1:E11of the first sheet. If everything lands in column A, select it and use Data > Text to Columns with the semicolon as the delimiter. Then save the workbook in.xlsxformat (File > Save As).Article;Categorie;Date;Quantite;PrixUnitaire Ramette papier;Papeterie;06/01/2026;20;4,5 Stylos (boite);Papeterie;08/01/2026;15;6 Cartouche encre;Informatique;12/01/2026;4;32 Classeurs;Papeterie;15/01/2026;30;2,5 Cle USB;Informatique;20/01/2026;10;9 Agrafeuse;Bureau;22/01/2026;5;12 Post-it;Papeterie;27/01/2026;40;1,5 Souris;Informatique;29/01/2026;6;15 Lampe de bureau;Bureau;02/02/2026;3;25 Calculatrice;Bureau;05/02/2026;8;11- Rename the sheet to
Achats. - Make row 1 bold and adjust the column widths.
- Apply the Long date format to the
Datecolumn (C2:C11). - Apply the Currency format with 2 decimals to the
PrixUnitairecolumn (E2:E11). - Freeze the top row.
- Select E2:E11 and read the status bar.
- The sheet is named Achats and row 1 stays visible when scrolling
- C2 displays mardi 6 janvier 2026
- E2 displays 4,50 € and E4 displays 32,00 €
- The status bar shows Count: 10 for the selection E2:E11
- Rename the sheet to
A left-aligned amount
In a column of amounts, one cell shows 45 left-aligned with a small green triangle. What is going on?
- The cell is in Currency format
- The number is stored as text and risks being ignored by calculations
- The cell contains a formula
- The column is too narrow
Displayed value and real value
In a new sheet:
- In A1, enter
=1/3. - Apply the Number format with 2 decimals to A1.
- In A2, enter
0,33. - In B1, enter
=A1*3and in B2, enter=A2*3. Apply 2 decimals to B1 and B2. - Compare B1 and B2 and explain the difference in one sentence in cell D1.
- A1 and A2 both display 0,33
- B1 displays 1,00 and B2 displays 0,99
- D1 explains that A1 actually contains 0,333333… and that the format only rounds the display
- In A1, enter
End-of-lesson quiz
What does the range B2:D5 designate?
- Only cells B2 and D5
- The rectangle of 3 columns and 4 rows between B2 and D5
- Column B down to row 5
A cell contains 0,2 and is formatted as a Percentage. Which value is used in a calculation?
- 20
- 0,2
- 20 %, that is 20
How does Excel store a date?
- As text
- As a number of days since January 1, 1900
- As three separate numbers
The rest of the course
- Formulas and Relative, Absolute and Mixed References20 min
- First Functions: SOMME (SUM), MOYENNE (AVERAGE) and SI (IF)20 min
- Sorting, Filtering and Conditional Formatting20 min
- Simple Charts15 min