一道巧算题2004.05×1997.05-2001.05×1999.05
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![一道巧算题2004.05×1997.05-2001.05×1999.05](/uploads/image/z/1737698-50-8.jpg?t=%E4%B8%80%E9%81%93%E5%B7%A7%E7%AE%97%E9%A2%982004.05%C3%971997.05%EF%BC%8D2001.05%C3%971999.05)
一道巧算题2004.05×1997.05-2001.05×1999.05
一道巧算题
2004.05×1997.05-2001.05×1999.05
一道巧算题2004.05×1997.05-2001.05×1999.05
=2004.05*1999.05 - 2004.05*2 - 2001.05*1999.05
=(2004-2001)*1999.05 - 2004.05*2
=3*1999.05 - 2*2004.05
=3*1999 + 3*0.05 - 2*2000 -2*4.05
=3*2000 - 3 + 0.15 - 2*2000 -8.10
=2000 - 3 + 0.15 - 8.10
=2000 +0.15 - 11.10
=1989.05