How we check every answer

A wrong answer in exam prep costs you points. So no number on this site is typed in by hand.

1. 1. Every number is computed in code

   Each kind of problem (present value, bond price, NPV, IRR, MIRR, WACC, payback and the rest) has its own small solver with its own tests. No answer is worked out by hand in the text.

2. 2. The walkthrough has to match

   A problem is stored as data: the question, its inputs, the computed answer and the walkthrough steps. If a walkthrough and the code ever disagree, the code wins and the walkthrough is rewritten.

3. 3. Wrong choices come from real mistakes

   Each wrong answer is what a specific slip produces, like using the before-tax cost of debt or discounting one year too many. That's why the feedback can name your mistake and send you to the section that fixes it.

4. 4. Videos and games use the same solvers

   The numbers on screen, in the narration and in every game round come from the same code as the walkthroughs, so they always agree.

5. 5. Automatic checks before anything goes live

   Before content is published, scripts re-run the solver tests and confirm that every problem has exactly one correct choice, no number is left blank, every video's captions cover the whole video and its chapters point at real questions.

If something you bought doesn't work, or has an error we can't fix quickly, you can get a refund within 14 days of purchase. Refund policy