Open a blank workbook and you're looking at a coordinate system. Columns run across the top, labelled with letters: A, B, … Z, then AA, AB, … all the way to XFD. Rows run down the side, numbered 1 to 1,048,576. That makes 16,384 columns and 1,048,576 rows, or just over 17 billion cells in a single sheet. You'll never fill them, but knowing the ceiling heads off a certain kind of panic ("did my data get cut off?").
Every cell has an address made of its column letter followed by its row number, and the letter always comes first. A1 is the top-left corner, C5 is column C row 5, and AZ1200 is column AZ row 1200. This is called A1 notation, and every formula speaks it.
How do formulas use cell addresses?
Why does the order matter, and why letters then numbers? Because a formula refers to cells by these addresses, and the whole idea of a spreadsheet is that a cell can hold a formula that points at other cells. Type =C5*C6 into D5 and the cell holds an instruction instead of a number: "whatever is in C5, multiply by whatever is in C6, and show the result here." Change C5 and D5 updates itself. That live pointer, multiplied across thousands of cells, is the reason spreadsheets conquered finance. The address is the pointer. Learn to read and write addresses cold.
Only one cell is active at any moment. It's outlined in green, and its address shows in the Name Box, the small white box at the far left of the formula bar, just left of the fx. It looks like decoration. It isn't. Type any address into the Name Box and press Enter, and Excel jumps there instantly. Type Z500, press Enter, and you're at Z500 no matter where you were. It's the fastest way to reach a distant cell, and the first mouse-avoidance habit to build.
Advertisement
How do ranges work, and what is R1C1?
A range is a rectangle. A contiguous block of cells is written as top-left:bottom-right, so A1:C10 means the ten-row, three-column rectangle from A1 to C10, which is 30 cells. A whole column is C:C and a whole row is 5:5. The colon is the range operator, and you'll read it as "through". SUM(A1:A20) means "sum everything from A1 through A20." Non-adjacent cells are joined with a comma, the union operator, as in SUM(A1:A10, C1:C10). Get comfortable reading a range aloud as a shape.
Half of debugging a formula is realising it points at the wrong rectangle.
Excel also has a second dialect, R1C1 notation, where both axes are numbered and R5C3 means row 5 column 3. You'll almost never turn it on (File ▸ Options ▸ Formulas ▸ "R1C1 reference style"). Still, learn to recognise the name. Macros and some error messages speak it. A1 is the analyst's default, so leave it there.