UNO plans a gathering

UNO plans a gathering. However there is threat of terrorist attack. So security guard who is a mathematical plans somethings to secure the place. A terrorist stands nearby the door where 1st ambassador comes , the security guard said 'twelve' and ambassador replied with 'six'. 2nd ambassador comes , the security guard said 'six' and ambassador replied with 'three'. The terrorist thinks its enough and walks to the door. The security person said 'eight' , terrorist replied 'four' and get immediately arrested. why ?

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #21904