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Legal Info and Quality Assurance


Our calculator software was written from the ground up with accuracy in mind. Whenever releasing a new version, we verify it by running several hundred tests based on real problems. Needless to say, we are very confident in the correctness of the solutions. The calculators were initially released in January 2004, and to date we have not encountered a single error.

Nevertheless, it is impossible to guarantee correctness in a system this complex. As a result, you should not use the calculators in any way which may put people, property, or anything of significant value at risk.

We log the input and output of the calculators, and periodically use this log data to improve our testing.

How We Test

We have a rigorous testing procedure that runs automatically whenever we release a new version of the following calculators:

There are two parts to the procedure:
  1. Unit Tests. Each of these tests confirms that a particular feature of a calculator is working as intended. Today we have over 650 Unit Tests.
  2. Problem Level Tests. Each of these is a real problem that has been entered into one of our calculators in the past. We enter each of these problems into the calculator, and automatically check that the answer matches our answer key. Today we have over 300 Problem Level Tests.

More Information

If you have any questions or comments on the calculator or the information provided above, please use the Feedback Form

Home Lessons Calculators Worksheets Resources Feedback Algebra Tutors