Numbers are only part of the problem
The tools apply formulas to the inputs supplied. They cannot determine whether a measurement is accurate, a rate matches a contract, or a selected formula describes a real situation. Check those assumptions before interpreting the result.
Worked examples explain methods using simplified values. They are not claims about a particular financial product, engineering design, legal requirement or personal situation.
Precision and supported inputs
Most numerical tools use JavaScript floating-point arithmetic and show rounded results. Some written decimal and fraction operations use exact integer arithmetic within specific limits. Each tool describes its accepted range.
A displayed approximation is not an exact symbolic proof. Algebra solvers accept a bounded set of expressions; a rejected input may need another method rather than a different numerical answer.
Financial estimates
Loan, mortgage and interest pages assume the rate and schedule described beside the inputs. Fees, changing rates, taxes, insurance changes or additional cash flows may be excluded. An estimate is not a quote, approval, forecast or professional recommendation.
Compare the modeled inputs with the actual terms you are working from. Preserve unrounded values through intermediate steps and apply the rounding rules relevant to your use case.
Important decisions and corrections
For decisions involving significant money, safety or other consequential outcomes, use appropriate authoritative information and independent checks. The site does not claim professional certification of every formula or input combination.
If an example or result appears inconsistent, the Contact page can help you prepare the exact inputs and expected output for a correction report. It currently provides local report preparation rather than message delivery.