Concept:Use complement rule: P(at least one 1)=1−P(no 1 on any die).Explanation:Total outcomes when four dice are thrown = 64=1296.Probability of not getting 1 on a single die = 65​.For four dice, P(no 1)=(65​)4=1296625​.Thus, P(at least one 1)=1−1296625​=12961296−625​=1296671​.Answer:1296671​