6.12.3.27.21.10.15.30 Find out the unusual numbers.

(1) Every number in this column is a multiple of 3 except 10.

(2) Starting from the second item in this column, each item is equal to the adjacent previous item plus 1, 2, 3, 4, 5, 6, etc. So the sixth number should be 12+5= 17, isn't it?

16. So, 16 is a different number.

So the answer is: (1) "Different" is: 10.

(2) Unusual: 16.