Subtract till 400

Calculate:

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

240	-	146	=
230	-	107	=
346	-	60	=
138	-	3	=
336	-	142	=
233	-	36	=
154	-	98	=
277	-	139	=
220	-	47	=
70	-	42	=