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简便计算219×99和89×99十59和43+43×99

可以把后面的当成是1X43,这样子就容易理解简便方法了 99X43+43 =(99x43).+(1x43) =(99+1)x43 =100x43 =4300

43+43×99简便计算 =43x100 =4300

43+43×99 =43×1+43×99 =43×100 =4300

=99x43+43x1 =(99+1)x43 =100x43 =4300

99x43+43 =(99+1)x43 =100×43 =4300

43+43×39 =43×(39+1) =43×40 =1720

=43x(99+1) =43*100 =4300

43+43x99 =43x(1+99) =43x100 =4300 解题思路: 这是乘法分配律的逆运算 乘法分配律 字母表示:(a+b)×c=a×c+b×c 变式:(a-b)×c=a×c-b×c

=43x(75+26-1) =43x100=4300

(1)42×(200+5)=42×200+5×42=8400+210=8610;(2)57×18+43×18=(57+43)×18=100×18=1800;(3)(125-30)×8=125×8-30×8=1000-240=760;(4)25×43=25×(40+3)=25×40+25×3=1000+75=1075;(5)57×99+57=57×(99+1)=57×100=5700;(6)46×1...

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