10 people meet and shake hands

10 people meet and shake hands. The maximum number of handshakes possible if there is to be no “cycle” of handshakes is (A cycle of handshakes is a sequence of k people a1, a2, ……, ak (k > 2) such that the pairs {a1, a2}, {a2, a3}, ……, {ak-1, ak}, {ak, a1} shake hands).

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #56796