1.简便方法计算下面各题. 101X9.87 1.25X0.25X3.21.简便方法计算下面各题. 101X9.87 1.25X0.25X3.2 200.2X7.8一7.8X0.2
问题描述:
1.简便方法计算下面各题. 101X9.87 1.25X0.25X3.2
1.简便方法计算下面各题. 101X9.87 1.25X0.25X3.2 200.2X7.8一7.8X0.2
答
101X9.87
=(100+1)×9.87
=100×9.87+9.87
=987+9.87
=996.87
1.25X0.25X3.2
=(1.25×0.8)×(0.25×4)
=1×1
=1
200.2X7.8一7.8X0.2
=(200.2-0.2)×7.8
=200×7.8
=156