7.81×11+0.78×90巧算

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7.81×11+0.78×90巧算
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7.81×11+0.78×90巧算
7.81×11+0.78×90巧算

7.81×11+0.78×90巧算
先把7.81拆成7.8和0.01
(0.78×11+0.78×9)×10 = 0.78×(11+9=20)×10 = 7.8×20 = 78×2 = 156
再加上7.81中剩下的0.01×11=0.11
156+0.11=156.11

7.81×11+0.78×90=7.8×11+7.8×9+0.01×11=7.8×20+0.11=156.11

7.81分成7.8和0.01,后面的改改成7.8*9,然后提取公因式,变成7.8*20 0.01*11

7.81×11+0.78×90
=(7.81*10+7.81)+(0.78*100-0.78*10)
=(78.1+78)+(7.81-7.8)
=156.1+0.01
=156.11

7.81×11+0.78×90
=7.8×11+0.01×11+7.8×9
=7.8×(11+9)+0.01×11
=7.8×20+0.11
=156+0.11
=156.11