During the execution of the exercises we keep track of the 1) total *number of exercises* performed, 2) *correct answers*, 3) *incorrect answers*, and 4) *total answers* (correct + incorrect answers).

The formula used to calculate the score is:

**score = correct answers / total number of answers * 100**

An example:

Correct answers: | 10 |

Incorrect answers: | 2 |

Total number of answers: | 12 |

Score = | 10 / 12 x 100 = 83 |

New option, *Retry in case of error*:

In case of error, if Retry in case of error is not selected: |
The answer is counted as incorrect, the correct answer is displayed and the next exercise is presented. |

In case of error, if Retry in case of error is selected: |
You can retry as many times as you want. Each failed attempt is counted as an incorrect answer. If it is finally answered correctly a correct answer is added. The total number of answers may add up to more than the total number of exercises. For example, two incorrect answers are given, but the correct answer is given in the third attempt. The total number of exercises would be 1, correct answers 1, incorrect answers 2 and total answers 3. |

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

José Rodríguez Alvira.