If you examine the numbers in the question above very well, you will discover that thy have a distinctive pattern. The pattern is this, you add 3 to the first number and then you multiply the next by 2. Lets go over the numbers now: 6 + 3 = 9 9 * 2 = 18 18 + 3 = 21 21 * 2 = 42 42 + 3 = 45 45 * 2 = 90 90 + 3 = 93 93 * 2 = 186, etc. Thus, the next number after 45 is 90.
