21:3=7 ( 21-3-3-3-3-3-3-3=0 )
7×3=21
36:4=9 ( 36-4-4-4-4-4-4-4-4-4=0 )
9×4=36
42:6=7 ( 42-6-6-6-6-6-6-6 =0 )
7×6=42
49:7=7 ( 49-7-7-7-7-7-7-7=0 )
7×7=49
63:7=9 ( 63-7-7-7-7-7-7-7-7-7=0 )
9×7=63
56:8=7 ( 56-8-8-8-8-8-8-8=0 )
7×8=56
54:6=9 ( 54-6-6-6-6-6-6-6-6-6=0 )
9×6=54
81:9=9 ( 81-9-9-9-9-9-9-9-9-9=0 )
9×9=81
