首先更正一下 2分之3的表达方法是3/2 不是2/3
之字后面的数字在/前面
(1)2.1×0.5÷4.2
=2.1÷4.2×0.5
=0.5×0.5
=0.25
(2)1002×355
=(1000+2)×355
=355000+710
=355710
(3)0.8÷3/2 +1.6÷3/2
=(0.8+1.6)÷3/2
=12/5÷3/2
=8/5(5分之8)
首先更正一下 2分之3的表达方法是3/2 不是2/3
之字后面的数字在/前面
(1)2.1×0.5÷4.2
=2.1÷4.2×0.5
=0.5×0.5
=0.25
(2)1002×355
=(1000+2)×355
=355000+710
=355710
(3)0.8÷3/2 +1.6÷3/2
=(0.8+1.6)÷3/2
=12/5÷3/2
=8/5(5分之8)