回复 1楼gokgs的帖子 43 * 44 * 45 * 46 * 47 / 2020 = 43 * 11 * 9 * 46 * 47 / 101 = (43 * 47) * (11 * 46) * 9 / 101 = (45^2 - 2^2) * 506 * 9 / 101 = (2025 - 4) * 506 * 9 / 101 = 2021 * 506 * 9 / 101 = 1 * 1 * 9 (mod 101) = 9 (mod 101) = 180 (mod 2020) Zorua 发表于 2021-09-26 16:15
43 * 44 * 45 * 46 * 47 / 2020 = 43 * 11 * 9 * 46 * 47 / 101 = (43 * 47) * (11 * 46) * 9 / 101 = (45^2 - 2^2) * 506 * 9 / 101 = (2025 - 4) * 506 * 9 / 101 = 2021 * 506 * 9 / 101 = 1 * 1 * 9 (mod 101) = 9 (mod 101) = 180 (mod 2020)
牛, 谢谢!
这是美国的竞赛题吗 有点难