201.1乘1999-2012 乘199.8的简便计算

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201.1乘1999-2012 乘199.8的简便计算

201.1乘1999-2012 乘199.8的简便计算
201.1乘1999-2012 乘199.8的简便计算

201.1乘1999-2012 乘199.8的简便计算
201.1×1999-2012 ×199.8
=2011×199.9-2012 ×199.8
=(2012-1)×199.9-2012 ×199.8
=2012×199.9-199.9-2012 ×199.8
=2012×(199.9-199.8)-199.9
=2012×0.1-199.9
=201.2-199.9
=1.3

201.1×1999-2012 ×199.8
=0.1×[(2012-1)×1999-2012×(1999-1)]
=0.1×[2012*1999-1999-2012*1999+2012]
=0.1×13
=1.3

201.1乘1999-2012 乘199.8
=(2012-1)1999-2012(1999-1)
=2012*1999-1999-2012*1999+2012
=3

201.1 × 1999- 2012 × 199.8
=2011×199.9 -2012 × 199.8
=2011×199.8+2011×0.1- 2012×199.8
=201.1-199.8
=1.3