Rule of Three

Solve proportionality problems instantly.

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Enter 3 values to find the 4th.

How to use the Rule of Three

  1. Identify the quantities (e.g., if 10kg cost $20, how much do 5kg cost?).
  2. Fill in fields A and B with the first relationship (A=10, B=20).
  3. Fill in field C with the known value of the second relationship (C=5).
  4. The system will calculate the value of X automatically.

Features

  • Automatic X Calculation
  • Formula Visualization
  • Decimal Support
  • Didactic Interface

Frequently Asked Questions

What is Rule of Three?

It is a mathematical method to find a fourth unknown value when you have three known and proportional values.

Is this calculator direct or inverse?

This tool calculates the DIRECT Rule of Three (when one quantity increases, the other also increases). E.g., the more gas, the further the car goes.

When to use?

To adapt cooking recipes, calculate fuel consumption, convert currencies manually, or solve exam questions.

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