Students A, B and D form a circle and report in turn. The declaration order of Party A, Party B and Party D is 1234, and so on. When the report number is 50, the report ends. Then the number of A newspapers can be expressed by 1+4*N less than or equal to 50, so the number of N newspapers is less than 12, and students whose newspaper number is an integer multiple of 3 should clap their hands once. Ask how many times a student should clap his hands, (1+4 * n)/3 = (1+n)/3+n, so only when N=2, 5, 8, 1 1, the number reported by a student is an integer multiple of 3.