选数填空 10 20 30 40 50 60 70 80 _×_=800 _×_=1200 _×_=3500 _×_=4200 _×_=2800 _×_=2400.

问题描述:

选数填空
10   20    30     40    50      60     70      80
______×______=800
______×______=1200
______×______=3500
______×______=4200
______×______=2800
______×______=2400.

20×40=800
30×40=1200
50×70=3500
60×70=4200
40×70=2800
40×60=2400
故答案为:20,40,30,40,50,70,60,70,40,70,40,60.