Adding till 400

Calculate:

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

224	+	128	=
112	+	281	=
70	+	80	=
86	+	84	=
24	+	19	=
88	+	109	=
145	+	96	=
129	+	183	=
130	+	187	=
62	+	36	=