2009/(2009+2009分之2010)用简算 速度!

问题描述:

2009/(2009+2009分之2010)用简算 速度!

=2009/(2009+(2009+1)/2009)
=2009/(2009+1+1/2009)
=2009/(2010+1/2009)
=2009/2010+1
=(2010-1)/2010+1
=1-1/2010+1
=2-1/2010
=4019/2010