expression, godan verb (-ru)
speculate; make an educated guess; gamble on a hunch
Used when someone bets on a likely outcome based on intuition or partial information, often in contexts like exams, predictions, or risky decisions. The related expression 山を掛ける is similar.
See also: 山を掛ける
試験に出そうな問題を山を張って勉強した。
I studied by guessing which questions might appear on the exam.
彼は選挙の結果を山を張って、見事に当てた。
He speculated on the election results and got them exactly right.