Anatomy of a formula
Every Excel formula starts with =. After that comes any combination of values, cell references, operators, and function calls — for example =SUM(A1:A10) * 2.
Excel evaluates the formula and shows the result in the cell, while the formula itself stays visible in the formula bar.
Cell references
A1 refers to the cell at column A, row 1. A1:A10 is a range. Sheet2!A1 is a cell on another sheet. [Workbook.xlsx]Sheet1!A1 refers to another workbook.
References update automatically when you insert or delete rows and columns — which is usually what you want, and occasionally what breaks a model.
Absolute vs relative references
A1 is relative — drag the formula down and it becomes A2, A3, and so on. $A$1 is absolute and stays put. $A1 locks the column; A$1 locks the row.
Mixed references are the secret to building one formula that fills a whole grid — common in tax tables and multiplication-style layouts.
Operators and order of operations
Arithmetic operators: + - * / ^ %. Comparison: = <> < > <= >=. Text concatenation: &. Reference: : (range), , (union), space (intersection).
Excel follows standard mathematical precedence: parentheses first, then exponents, then multiplication and division, then addition and subtraction. When in doubt, add parentheses.
Functions
A function is a named operation that takes arguments and returns a value: SUM(range), IF(test, then, else), VLOOKUP(lookup, table, col, exact).
Functions can be nested — the result of one becomes an argument to another: =IF(SUM(A1:A10)>0, "Positive", "Empty"). Excel evaluates from the inside out.
Recalculation
By default, Excel recalculates the whole dependency graph whenever any input changes. For large models you can switch to manual calculation (Formulas → Calculation Options) and press F9 to recalc on demand.
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