Whats the last common multple of 2,5,6,9 and 9 is

"9 and 9?"  Did you possibly mean {2, 5, 6, 9}?

The least common multiple of a set of numbers is the smallest integer that can be divided evenly by all of the numbers.  In this case, when I saw the 9 and 5, I thought, "45!"  but 45 is not evenly divisible by 2 or 6.  

So, I tried 90.  90 is indeed divisible by {2, 5, 6, 9}, and is thus the LCM.

Look up and review "Least common multiple."