doubles
What is 20 plus 20?
40
123+9
132
93-9
84
259-10
249
What is 300 plus 300?
600
82+6
88
158-11
147
600-15
585
What is 4000 plus 4000?
8000
258+10
268
86-12
74
24+24
48
What is 12 plus 12?
24
66+9
75
23-4
19
999-8
991
What is 600 plus 600?
1200
1057+4
1061
74-15
59
864-40
824