42 = 2 * 3 * 7 * 1
105 = 3 * 5 * 7 * 1
НОД (42 и 105) = 3 * 7 * 1 = 21
588 = 2 * 2 * 3 * 7 * 7 * 1
252 = 2 * 2 * 3 * 3 * 7 * 1
НОД (588 и 252) = 2 * 2 * 3 * 7 * 1 = 84
680 = 2 * 2 * 2 * 5 * 17 * 1
612 = 2 * 2 * 3 * 3 * 17 * 1
НОД (680 и 612) = 2 * 2 * 17 * 1 = 68