... Bi 16: Tỡm ba ch s tn cựng ca 2004200 Gii: (2004, 5) = (tớnh cht 6) 2004100 chia cho 125 d 2004200 = (2004100)2 chia cho 125 d 2004200 ch cú th tn cựng l 1 26, 251, 3 76, 501, 62 6, 751, 8 76 Do ... 1,2,3 , 5, S = 1 1 + + + + 1.2 2.3 3.4 99.100 6, S = 4 + + + 5.7 7.9 59 .61 7, A = 5 5 + + + + 11. 16 16. 21 21. 26 61 .66 8, M = 1 1 + + + + 2005 3 3 9, Sn = 1 + + + 1.2.3 2.3.4 n(n +1)(n + 2) ... p + 2, p + 6, p + 8, p + 14 c) p + 6, p + 8, p + 12, p + 14 d) p + 2, p + 6, p + 8, p + 12, p + 14 e) p + 6, p + 12, p + 18, p + 24 f) p + 18, p + 24, p + 26, p + 32 g) p + 4, p + 6, p + 10,...