Вычислите рациональным способом:

1) 425*88+139*25+425*12+139*75;

2) 680*17+300*34+680*33+300*16

3) 923*60-923*50+77*27-77*17

1) = 425 (88+12) + 139 (25+75) = 425*100+139*100=100 (425+139) = 100*564=56400

2) = 680 (17+33) + 300 (34+16) = 680*50+300*50=50 (680+300) = 50*980=49000

3) = 923 (60-50) + 77 (27-17) = 923*10+77*10=10 (923+77) = 10*1000=10000