Snelle erbijsommen en erafsommen tot 20
In de mix
1.
12
2
+
=
2.
16
3
+
=
3.
12
1
+
=
4.
19
1
+
=
5.
15
14
–
=
6.
13
4
+
=
7.
15
3
+
=
8.
14
4
+
=
9.
16
4
+
=
10.
12
2
+
=
11.
16
4
+
=
12.
15
12
–
=
13.
15
14
–
=
14.
12
4
+
=
15.
18
12
–
=
16.
15
2
+
=
17.
14
1
+
=
18.
18
16
–
=
19.
14
4
+
=
20.
16
2
+
=
21.
16
15
–
=
22.
18
14
–
=
23.
18
15
–
=
24.
14
1
+
=