Final answer:
A 'full fail' would typically mean that all items in a set have failed to meet a certain standard, so the number of failed items would equal the total number of items in the set.
Step-by-step explanation:
The question seems to be asking about a situation in which there is a set of items being checked and all items in the set have failed the check. Without additional context or information on the specific process or criteria for the check, it is difficult to determine the exact number of failed items.
Normally, a 'full fail' would imply that every item in the set has not met the required standards. Therefore, if you have a batch of 100 items and they all fail, then 100 items would have failed. If knowing the total number of items is necessary, further clarification from the question asker is required.