例1:999+99+9练习1:19+199+1999+19999练习2:1966+1976+1986+1996+20062010+2005+2004+2003+1998(1)6752 (2)25(784)(3)72125 (4)90001258(5)40025 (6)2536(1)10327 (2)76102 (3)3600254 (4)9935(1)5225= (2) 197171= (3)25288125= (4)2532125= (1)25192125= (2)304+(166-104)= (3)282135+365282= (4) 1833-3-382= 。