Use and limitations

These free educational tools explain methods and arithmetic. They are not a professional engagement, personalized advice or a guarantee of results.

Check the assumptions

Examples are invented for explanation unless specifically identified otherwise. Verify your inputs and consult the relevant provider, official documentation or qualified professional for decisions requiring specialist advice. A calculator output does not establish market prices, legal compliance, revenue or suitability.

Availability and corrections

Content and tools may change as errors are corrected or methods improve. Keep the assumptions with any saved result. Report problems through our contact page.