Adding till 100

Calculate:

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

27	+	25	=
37	+	39	=
8	+	11	=
24	+	20	=
20	+	61	=
7	+	7	=
21	+	54	=
15	+	12	=
10	+	9	=
17	+	20	=