Adding till 400

Calculate:

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

55	+	41	=
158	+	53	=
108	+	55	=
31	+	34	=
39	+	37	=
49	+	46	=
22	+	21	=
138	+	114	=
90	+	104	=
39	+	82	=