Adding till 100

Calculate:

The number of examples:
Numerical difficulty:
Range of values:
Multiplicity:

38	+	33	=
2	+	4	=
13	+	18	=
47	+	53	=
34	+	22	=
35	+	51	=
6	+	7	=
31	+	17	=
29	+	28	=
7	+	8	=