Combinations of 18 numbers with 9 deletions/6 bets 

 Out of 80 numbers, we randomly select 18 and spread them over 6 bets of 9 deletions each.  The combinations can be used in various number games

1 2 3 4 9 10 14 15 16
5 6 7 8 12 14 16 17 18
1 3 6 8 11 13 14 16 17
2 4 5 8 9 10 13 15 17
1 3 5 7 9 10 11 12 18
2 4 6 7 11 12 13 15 18
Replace the numbers from 1 to 18 with the desired numbers