Spreadsheets: Rows, Columns and a Formula That Updates Itself
A spreadsheet holds values in cells and formulas that refer to those cells by name. Change one value and everything computed from it recalculates, which is what makes a sheet a model rather than a table.
What a learner can do afterwards
- Write a formula that refers to cells rather than to numbers typed into the formula
- Change one input and predict, before looking, which cells will change
- Copy a formula down a column and say what happened to the references it contains
1 · Read
A spreadsheet is a model, not just a table. When you plan snacks for a class party, you type a formula into a cell, starting with an equals sign, and the sheet works out the total cost. The whole file is called a workbook, and one grid tab inside it is called a worksheet.
Every formula starts with an equals sign and may name cells, like =A1+A2. Use star for times and slash for divide, with brackets to set order.
A1 holds 4 and A2 holds 7, so =A1+A2 shows 11. Change A1 to 10 and the answer updates to 17 all by itself. Copy that formula down a column and its names shift with it, so one rule prices a whole list.
Copy a formula down a column and its names shift with it. Copying down is how one rule prices a whole list.
Point formulas at cells, not fixed numbers, and the sheet updates itself when inputs change.
The rewritten readings were written for this dataset.
More to read
Calculating with spreadsheets
A spreadsheet works like a calculator. You type a formula into a cell, and it works out the answer for you. But a spreadsheet can do something a calculator cannot: a formula can point at other cells instead of using plain numbers.
Say cell A1 holds the number 4 and cell A2 holds the number 7. In cell A3 you could type =A1+A2. The sheet shows 11. If you change A1 to 10, cell A3 updates all by itself and shows 17. You never touched A3. It recalculated because its formula refers to the cells, not to fixed numbers.
This is why people say a spreadsheet is a model, not just a table. A table only stores numbers. A model stores the rules for how numbers depend on each other, so when one input changes, every answer that depends on it changes too.
To enter a formula, click a cell, type the equals sign, then the cell names and the math, like =B2*C2. Press enter and the answer appears. Try solving the same problem with different numbers by changing just the input cells. You will never have to retype the formula.
Names for spreadsheet tools
A cell reference identifies a cell using a column letter followed by a row number. B3 is an example. Using that reference in a formula lets the formula read the cell's value.
Relative references adjust when a formula is copied. Copying =A1+B1 into the cell one row below produces =A2+B2. This lets you reuse a calculation along a column.
Absolute references keep their location when copied. Dollar signs mark them, as in $A$1. This helps when copied formulas all need one cell's value, such as a tax rate.
Functions are named calculations you can use in formulas. AVERAGE totals numerical values and divides by their count.
A worksheet has a single grid arranged in rows and columns. A workbook is the file that can hold several worksheets, shown as tabs.
Build calculations that can update
Cells store values in a spreadsheet. Formulas describe calculations, while functions such as SUM and AVERAGE provide common calculations without writing them out yourself.
The file is called a workbook. Each worksheet is a grid shown on its own tab, and several worksheets can share a workbook.
You can assign a name to a range of cells to make formulas clearer. If B2:B20 is named Sales, =SUM(Sales) can replace =SUM(B2:B20).
With automatic recalculation enabled, changing a referenced value updates the formula's result. If recalculation is set to manual, you must request it. Cell references let calculations respond to changed data instead of leaving answers as fixed, typed entries.
2 · Watch
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Optional connections
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.