Answer:
excuse me friend, for you to get the next pattern, you have to know what has been done from this number to the other number.
so from 3 to 6 it was a + 3 from 6 to 11 it was a+5 from 11 to 18 it was a + 7.
if you look carefully,2,3 and 7 are odd numbers meaning that the next pattern should be an odd number (9) which will be added to the numbers at the top.
you can still say that they were increasing by 2. (3 to 5 to 7)
so you can add 2 to 7 to get a nine. then,add 9 to 18 to get a 27.
Good day.