Question

7.81x49-78.1x38+0.781x90

Answer 1

7.81×49-78.1×38+0.781×90计算如下：
7.81×49-78.1×38+0.781×90
=7.81×49-78.1×38+7.81×0.1×90
=7.81×49-78.1×38+7.81×（0.1×90）
=7.81×49-78.1×38+7.81×9
=7.81×（49-38+9）
=7.81×（49+9-38）
=7.81×20
=156.2

Answer 2

7.81×49-78.1×38+0.781×90
=7.81×(49+9)-78.1×38
=7.81×(58-380)
=-7.81×322
=-8×322+0.19×322
=-2576+0.2×322-0.01×322
=-(2575-64.4)-3.22
=-(2510.6+3.22)
=-2513.82