if 2=6ˏ 3=12ˏ 4=20ˏ 5=30ˏ 6=42ˏ then 9 = ?
23=6. 34=12. 45=20. 56=30. 67=42. So 98=72
If 2 = 6, 3 = 12, 4 = 20, 5 = 30, and 6 = 42, then 9 = 90.