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Rule-of-three calculator
Find the fourth value in a direct proportion A:B = C:X.
Text and numbers
Text
Browser only
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How to use this tool
- Enter the requested values: A; B; C.
- Choose Calculate and review the result.
- Download the text result if useful. Reset restores the initial inputs and clears the result.
Examples
3:12 = 5:20.
Limitations
Runs entirely in your browser. Numeric calculations use IEEE-754 floating-point arithmetic; displayed values are rounded to 15 significant digits unless stated otherwise.
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