ADDITION Self-Correcting Quiz - THREES

1
0
+  3
2
3
+  3
3
2
+  3
4
1
+  3
5
3
+  3
6
3
+  7
7
7
+  3
8
5
+  3
9
3
+  8
10
3
+  9
11
3
+  6
12
3
+  2
13
6
+  3
14
9
+  3
15
3
+  0
16
3
+  1
17
3
+  5
18
4
+  3
19
8
+  3
20
3
+  4