1.9+19.9+199.9+1999.9+19999.9+1 =(1.9+0.1)+(19.9+0.1)+(199.9+0.1)+(1999.9+0.1)+(19999.9+0.1)+(1-0.5) =2+20+200+2000+20000+0.5 =22222.5
