# 4.7: Creating Formulas to Perform Calculations

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Perhaps the biggest benefit of using Excel is its ability to create formulas that, when written correctly, can dynamically update when predecessor data is updated. Formulas are mathematical calculations using data in the existing workbook to calculate new values. All formulas in Excel must begin with an equal sign (=), and can contain cell references, ranges of cell references, arithmetic operators, and constants as part of the formula’s syntax. Calculations in Excel follow normal math rules as it pertains to the order of operations rule. There are mnemonics available in various dialects to help decipher the order. The following graphics illustrate the order of operations rules and different formula syntax examples: