Go to the console and type:
ruby print_table.rb 8
The program accepts an argument that indicates the prime numbers to get (N). In this case is 8 but you can specify any number greater than zero. If N is not present, it's not an integer or it's less than 1, it will get the first 10 prime numbers.
As a result, a multiplication table will be printed out. For N = 8:
X 2 3 5 7 11 13 17 19
2 4 6 10 14 22 26 34 38
3 6 9 15 21 33 39 51 57
5 10 15 25 35 55 65 85 95
7 14 21 35 49 77 91 119 133
11 22 33 55 77 121 143 187 209
13 26 39 65 91 143 169 221 247
17 34 51 85 119 187 221 289 323
19 38 57 95 133 209 247 323 361
The first row and column are the N prime numbers, with each cell containing the product of the primes for the corresponding row and column.