4 * 120 = 4 * (100 + 20) = 4 * 100 + 4 * 20 = 400 + 80 = 480
3 * 230 = 3 * (200 + 30) = 3 * 200 + 3 * 30 = 600 + 90 = 690
делители числа:
9) 3,1,9
10) 1,2,5,10
12) 1,2,3,4,6,12
15) 1,3,5,15
18) 1,2,3,6,9,18
20) 1,2,4,5,10,20