Adding till 400

Calculate:

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

42	+	13	=
46	+	46	=
91	+	31	=
85	+	104	=
162	+	113	=
74	+	43	=
189	+	199	=
129	+	158	=
83	+	96	=
158	+	165	=