1.用简便算法计算393×99 67×39+32×39+39

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1.用简便算法计算393×99 67×39+32×39+39
1.用简便算法计算
393×99 67×39+32×39+39

1.用简便算法计算393×99 67×39+32×39+39
393×99
=393*(100-1)
=39300-393
=38907
67×39+32×39+39
=39*(67+32+1)
=39*100
=3900

393×(100-1)=39300-393
67×39+32×39+39=(67+32+1)×39=3900

393*(400-1)=38907
39*(67+32+1)=3900

393×(100-1)
=39300-393
=38907
(67+32+1)×39
=100×39
=3900