Questions with answers related to the number series

1. 49 , 1625 , 3649 , ?

Solution : Each term in the above series is combination of squares of 2 numbers i.e.

22 32 , 42 52 , 62 72 . So, our answer will be 6481.

2. Look at this series: 40, 40, 26, 26 , 12 , ? … What number should come next?

Solution:Answer is 12. Each number is repeated or firstly 0 is added to each number and then 14 is subtracted from it.

3. 2 , 4 , 11 , 37 , ?

Solution: (2*1) + 2 =4

(4*2) + 3 = 11

(11*3) + 4 =37

(37*4) + 5 = 153

4. 6 , 3 , 3, 4.5 , 9, ?

Solution : We see that no decreasing or increasing difference logic is applicable here. So, we find out the ratios of every term with its predecessor. We get the following values: 0.5 , 1 , 1.5 , 2 . This makes it clear that 9 should be multiplied by 2.5 in order to obtain the next number.

Therefore, the answer is 9* 2.5 = 22.5 .

5. 8 , 15 , 26 , 39 , ?

Solution: Let us start by finding out the difference between every pair of consecutive terms:

15-8=7

26-15=11

39-26=13

We observe that the difference is the series of prime numbers. According to this logic , 17 should be added to 39 to obtain the answer. Hence, the answer is 56.

6. Consider the series: 42, 40, 36, 34, 30, 28, … What number should come next?

Solution: 24 is the answer . we are performing the operations : – 2, -4. )

7. 24 , 30 , 36 , 42 , 54 , 60 , 68 . Find out the wrong term in the series.

Solution: Each term is the sum of 2 consecutive prime numbers.

24 = 11+ 13

30 = 13+ 17

36= 17+ 19

So, according to this logic, 54 is the wrong term. We should have 52 in its place.

8. 17 , ? , 102 , 408 , 2040 . Find out the missing number.

Solution: We can see that the series is increasing rapidly. Let us find out the ratios of every 2 consecutive terms.

2040/ 408 = 5

408/ 102 =4

102/ ? =3

Therefore , our answer is 34.

9. 49, 47, 45 , 42 , 40 ,38 , 35, 33 ,31 , 28, ? , ?

Solution: 26 24 is the answer. It is an alternating subtraction series where 2 is subtracted twice and then 3 is subtracted one and this pattern is continued.

10. 1 , 8 , 9 , 64 , 25 , 216 , ?

Solution: The answer for this is 49. The following pattern is being followed:

12 , 23 , 32 , 43 , 52 , 63 , 72.

11. 1 , 4 , 9 , 1 , 6 , 2 , 5 , ? , ?

Solution: At a first glance it is very difficult to see any kind of pattern here. Any kind of pattern among increasing, decreasing, product , square , cube etc does not seem to be working here.

But we can observe that 1 , 4 , 9 are squares of 1 , 2 , 3 respectively. And after that should come 16 but instead of that we have 1 ,6 . After that instead of 25 , we have 2, 5. So , we can come to the conclusion that when the squares start taking 2 digits, instead of writing them as a 2 digit number , we simply separate them into 2 different terms. So, our next term will be 3 ,6 .

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