1. Calculate.
2. Calculate. Be very careful.What did you find?
4
2
7
+
3
8
9
7
8
3
-
4
3
5
2
1
4
9
+
5
3
2
5
9
6
2
8
-
2
4
2
9
-
3
6
4
-
1
9
2
-
3
1
5
8
-
4
3
5
7
-
3
9
1
+
2
4
9
-
1
4
0
8
-
1
6
0
6
3
5
8
+
4
9
7
1
8
9
+
3
4
1
1
1
3
2
+
4
0
0
5
5
1
9
9
+
3
0
4
