Hello,

The only way I think I know how to do it, is by drawing up a s3 Cayley table and subbing in the numbers.

When I do that, i end up with;

12H = { 12, 13, 23 } = H12

13H = { 13, 23, 12 } = H13

23H = { 23, 12, 13 }

123H = { 123, 132, e} = H(123)

132H = { 132, e, 123}

Therefore, 3 cosets. Could some please confirm if this is ok for me to do it like this?