17/9÷[（4/9+1/2）×9/17]
=17/9÷(17/18*9/17)
=(17/9)*2
=34/9
1又2/3×1又2/5×1又2/7×1又2/9×1又2/11×…×1又2/199
=5/3*7/5*9/7*.199/197*201/199
=201/3
=67
（1+1/3+1/5+1/10+1/15+1/30）÷（1/2+1/4+1/6+1/12+1/20+1/60）
=[(30+10+6+3+2+1)/30]÷[(30+15+10+5+3+1)/60]
=(52/30)*(60/64)
=13/8
[17.1-17.2÷（3.1-0.7）]×0.6
=(17.1-17.2÷2.4)*0.6
=17.1*0.6-17.2/2.4*0.6
=10.26-4.3
=5.94
（2又2/9×4/5+2又2/9×6.2-5.8×2又2/9-1/5÷9/20）×9/20
=20/9*(0.8+6.2-5.8-0.2)*9/20
=0.8+6.2-5.8-0.2
=7-6
=1
2009÷2009又2009/2010+1/2011
=2009÷[2009*(1+1/2010)]+1/2011
=1÷(2011/2010)+1/2011
=2010/2011+1/2011
=1