In this sequence, the difference between each number is double the difference between the number that came prior to it in the sequence. For example,  and . Thus, the missing number must be greater than  by a difference of  and therefore 

In this sequence of numbers, there is an important pattern to recognize. In this sequence each number is a prime number, however the sequence skips every other prime number. Thus, the sequence begins with the prime number  and then skips the prime number  (which is the only even prime number) and goes to . From  the next prime number is , however since the pattern in this sequence skips every other prime number--the missing number is .      

In this sequence of numbers, there is an important pattern to recognize. Each number in this sequence is a composite number--however, the sequence skips every other composite number. Thus, the next composite number after  is --which is skipped because of the pattern, making the correct answer .

In this sequence of numbers, there is an important pattern to recognize. Each number is greater than the number prior to it by a margin of . In other words, each number in this list is a multiple of . Thus,  

In this sequence of numbers, there is an important pattern to recognize. Each number is greater than the number prior to it by a margin of . Thus, the correct answer is , because   

In this sequence of numbers, there is an important pattern to recognize. Each number is greater than the number prior to it by a margin of 9. Thus, the correct answer is  because . 

In this sequence of numbers, there is an important pattern to recognize. Each number is greater than the number prior to it by a margin of . Therefore, the missing number is , because 

In this sequence of numbers, there is an important pattern to recognize. Each number is greater than the number prior to it by double the difference between the two previous numbers.  is greater than  by a difference of , therefore the number that is missing must be greater than  by a margin of . Thus, the correct answer is . Notice that  is also less than  by a difference of 

In this sequence of numbers, there is an important pattern to recognize. Each number is less than the previous number by a difference that is double the margin between the previous two numbers. For example, the difference between  and  is  And, the difference between  and  is . Thus, the missing number must be less than  by a difference of --which means that  is the missing number. 

In this sequence of numbers, there is an important pattern to recognize. Each number is greater than the number prior to it by a margin of  Thus,