简便运算：
27×46÷79÷46×79÷27
=27*46/(79*46)*79/27
=27/79*79/27
=1
19961997×19971996－19961996×19971997
=19961996*19971996+19971996-19961996*(19961996+10001)
=19971996-19961996*10001
=19971996-199619960000-19961996
=10000-199619960000
=-199619950000
1994﹢199.4﹢19.94﹢1.994
=1.994*(1000+100+10+1)
=1.994*1111
=2215.334
9.1﹢9.2﹢9.3﹢9.4﹢……﹢10.7﹢10.8﹢10.9
=(9.1+10.9)*19/2
=20*19/2
=190
89﹢899﹢8999﹢89999﹢899999
=80+800+8000+80000+800000+9+99+999+9999+99999
=888880+111110-5
=999990-5
=999985