HCF is 1, and LCM is 810. This I could do in 2 seconds (may be a bit more!)
81, has a factor of 3 and its multiples. While 10 has no 3. So there is no commonprime number between 10 and 81. Once that happens, how many ever other numbers are there, HCF is 1.
For LCM, I noticed, LCM of 10,20,30 = 30. Sofinal answer for this series is LCM (30,81). I know,There is one 3 in 30, however we have more 3s in 81. And if that is removed LCM(30,81) = LCM(10,81). The last is 810, as both are co-primes!
Sorry - in the above, read 3 and its powers, rather than 3 and its muliples