Сделай группировку множителей 16*30 =, 42*20= , 12*40= , 25*16 = ,15*18= , 45*14 = , 13*60= , 45*20 = , 15*30 =,14*50=, пример 16*30=(3*10)*16=(3*16)*12=480

16*30 = 4*4*30 = 4*120 = 480
42*20 = 21*2*20 = 21* 40 = 840
12*40 = 2*6*40 = 2*240 = 480
25*16 = 25*4*4 = 100*4 = 400
15*18 = 5*3*9*2 = 5*2*3*9 = 10*27 = 270
45*14 = 45*2*7 = 90*7 = 630
13*60 = 13*6*10 = 78*10 = 780
45*20 = 45*2*10 = 90*10 = 900
15*30 = 3*5*30 = 3*150 = 450
14*50 = 7*2*50 = 7*100 = 700