①996+599-402
②7443+2485+567+245
③2000-1347-253+1593
④3675-(11+13+15+17+19)
①1870-280-520
②4995-(995-480)
③4250-294+94
④1272-995
①1000-547
②100000-85426
③11111111110000000000-1111111111
④78053000000-78053
①478-128+122-72
②464-545+99+345
③537-(543-163)-57
④947+(372-447)-572