Adding till 400

Calculate:

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

110	+	76	=
178	+	171	=
193	+	95	=
23	+	41	=
199	+	167	=
69	+	36	=
142	+	136	=
15	+	31	=
127	+	267	=
31	+	31	=