Multiplication till 400

Calculate:

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

16	×	17	=
9	×	9	=
12	×	15	=
20	×	7	=
13	×	17	=
18	×	21	=
14	×	13	=
21	×	17	=
9	×	10	=
9	×	12	=