Adding till 100

Calculate:

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

42	+	30	=
27	+	52	=
23	+	25	=
15	+	10	=
20	+	29	=
32	+	33	=
12	+	9	=
44	+	34	=
49	+	51	=
33	+	17	=