Adding till 400

Calculate:

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

261	+	130	=
188	+	210	=
169	+	181	=
28	+	42	=
256	+	96	=
209	+	181	=
21	+	62	=
9	+	5	=
48	+	27	=
162	+	161	=