Direct Proportion Calculator

What Direct Proportion Calculator does

Find a fourth value when two quantities vary in direct proportion.

Worked example

Calculation method

Equal ratios give a/b=c/x, so the unknown is obtained by cross multiplication and division.

Useful workflows

• Check a small teaching example and inspect intermediate results.
• Compare an independently calculated answer or software test fixture.
• Copy the result together with its input notation and selected options.

Limits and review checks

• Combinatorial, graph and search problems can grow exponentially and are intentionally size-limited.
• Confirm integer, modular, set-order, precision and rounding assumptions before comparing answers.
• Cryptography-related pages are educational demonstrations and must not generate or validate production security keys.

Frequently asked questions

Why is my input rejected?

Check separators, variable names, supported operators, numeric ranges and whether the selected algorithm requires integers.

Can I use this result in a high-stakes decision?

Use the tool for learning and independent checks. Verify legal, financial, safety or security decisions with an authoritative method and qualified reviewer.