两道用简便方法做的题！！！！！！！

56.8乘35.7+56.8乘28.5+64.2乘43.2

9999+6666乘21+3333乘55

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56.8*35.7+56.8*28.5+64.2*43.2
=56.8*(35.7+28.5)+64.2*43.2
=56.8*64.2+64.52*43.2
=64.8*(56.8+43.2)
=64.8*100
=6480

9999+6666*21+3333*55
=3333*3+3333*2*21+3333*55
=3333*3+3333*42+3333*55
=3333*(3+42+55)
=3333*100
=333300

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