Multiplication till 400

Calculate:

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

20	×	20	=
13	×	11	=
2	×	3	=
8	×	7	=
17	×	16	=
12	×	9	=
14	×	14	=
7	×	13	=
15	×	12	=
17	×	21	=