用简便算法计算下列算式. (1)108×92-42×8; (2)3.78×2.2+1.7×1.22+1.12×0.5.

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问题 用简便算法计算下列算式.
    (1)108×92-42×8;
    (2)3.78×2.2+1.7×1.22+1.12×0.5.

选项

答案(1)108×92-42×8 =(100+8)(100-8)-(50-8)×8 =1002-82-50×8+82 =10000-400 =9600 (2)3.78×2.2+1.7×1.22+1.12×0.5 =3.78×2.2+1.7×1.22+(1.22-0.1)×0.5 =3.78×2.2十(1.7+0.5)×1.22-0.1×0.5 =3.78×2.2+2.2×1.22-0.05 =(3.78+1.22)×2.2-0.05 =5×2.2—0.05 =11-0.05 =10.95

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