Best Interview Questions for Engineers

Here's a question that I sometimes ask an engineering candidate:

You have a list of 100 numbers with values in the sequence 1 to 100. Each number of the sequence appears once except that one value is missing and one value is repeated. Determine which value is missing and which one is repeated.

Notice that I didn't say anything about writing code. If asked,I will answer no questions like "are they in order?" and so forth.

For the engineer to ask the employer or the other way around?