Adding till 400

Calculate:

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

229	+	156	=
33	+	57	=
16	+	30	=
86	+	53	=
23	+	16	=
24	+	23	=
18	+	13	=
75	+	54	=
24	+	24	=
48	+	46	=