Prompt Technique "My Best Guess Is"

https://www.reddit.com/r/ChatGPT/comments/13ppc5k/try_the_my_best_guess_is_technique_for_80/

reported to reduce hallucinations by 80 percent

you can also ask an LLM to report own confidence, which may alert you to hallucination likelihood without forcing it to guess:
https://www.reddit.com/r/singularity/comments/11zhttl/why_is_this_graph_not_a_bigger_deal/

you can turn this own-confidence report into a classification task where it basically classifies it's own confidence level and therefore can autoclassify likely hallucinations (a common approach it to have it report "I don't know" or similar, or make a best guess)