(1) 9+0-0= (11) 4+1-2= (21) 8+1-5= (31) 5+4-0= (41) 4+5-6=
(2) 2+8-9= (12) 6+3-5= (22) 1+7-2= (32) 0+9-1= (42) 1+8-7=
(3) 2+3-0= (13) 2+6-4= (23) 5+0-1= (33) 7+3-8= (43) 2+7-5=
(4) 4+0-3= (14) 7+2-5= (24) 8+1-3= (34) 2+5-3= (44) 6+2-8=
(5) 6+1-4= (15) 2+3-2= (25) 5+3-4= (35) 9+1-3= (45) 4+1-3=
(6) 1+4-5= (16) 7+0-7= (26) 2+6-2= (36) 4+3-7= (46) 4+6-8=
(7) 7+1-8= (17) 1+6-0= (27) 1+1-0= (37) 1+8-1= (47) 2+7-8=
(8) 2+8-1= (18) 1+9-5= (28) 9+1-2= (38) 1+6-3= (48) 9+0-3=
(9) 5+3-0= (19) 8+0-6= (29) 8+1-1= (39) 5+1-6= (49) 7+1-5=
(10) 4+1-0= (20) 4+2-6= (30) 5+4-3= (40) 6+2-7= (50) 3+1-3=

标准答案:
(1)9 (2)1 (3)5 (4)1 (5)3 (6)0 (7)0 (8)9 (9)8 (10)5 (11)3 (12)4 (13)4 (14)4 (15)3 (16)0 (17)7 (18)5 (19)2 (20)0 (21)4 (22)6 (23)4 (24)6 (25)4 (26)6 (27)2 (28)8 (29)8 (30)6 (31)9 (32)8 (33)2 (34)4 (35)7 (36)0 (37)8 (38)4 (39)0 (40)1 (41)3 (42)2 (43)4 (44)0 (45)2 (46)2 (47)1 (48)6 (49)3 (50)1