高手来,数学题,要用简便方法

52.44*79.45+159*47.56+79.55*52.44
=52.44*(79.45+79.55)+159*47.56
=52.44*159+159*47.56
=159*(52.44+47.56)
=159*100
=15900
5/9*193+4/9*195
=5/9*193+4/9*193+4/9*2
=193+8/9
2001*20022002-2002*20012001
=2001*2002*10001-2002*2001*10001
=0
1.9+19.9+199.9+1999.9+19999.9
=2+20+200+2000+20000-0.5
=22222-0.5
=22221.5
1/1883+2/1883+......+1882/1883
=(1/1883+1882/1883 )+(2/1883+1881/1883)+......+(941/1883+942/1883)
=1+1+1+1+1+1+1+1+1+1+1+......+1
=1883
10.375*18.88+18.88*0.625-188.8*0.1
=10.375*18.88+18.88*0.625-18.88*1
=18.88*(10.375+0.625-1)
=18.88*10
=188.8