38х11 = 38 х (10+1) = 38х10 + 38х1 = 380 + 38 = 418
16х25 = 4х4х25 = 4х100 = 400
19х16 = (20-1) х16 = 20х16 - 1х16 = 320 - 16 = 304
38х11 = 38 х (10+1) = 38х10 + 38х1 = 380 + 38 = 418
16х25 = 4х4х25 = 4х100 = 400
19х16 = (20-1) х16 = 20х16 - 1х16 = 320 - 16 = 304