78X301的简便运算
3.用简便方法计算。401x31 78x201-78 35x301 -
=12431 78×201-78 =78×201-78×1 =78×(201-1)=78×200 =15600 35×301 =35×(300+1)=35×300+35×1 =10500+35 =10535
=12431 78×201-78 =78×201-78×1 =78×(201-1)=78×200 =15600 35×301 =35×(300+1)=35×300+35×1 =10500+35 =10535