Adding
99+1
100
17-5
12
4x4
16
6/3
1/2 +1/2
2/2 or 1
50+50+50+50
200
56-17
39
5x6
30
12/4
3
8/10-2/5
4\10
150+150
300
259-186
73
8x9
72
42/7
6
5/10+10/10
15/10 or 1 1/2 or 1 5/10
159+159+82
400
4321-1234
3087
11x11
121
63/7
9
6/8-1/4
4/8 or 2/4
238+262
500
9685-7346
2339
12x12
144
12/0
undefined
the official answer is undefined as the 0 is not the answer
3 1/5-2 2/10
1