# What Comes Next? Trivia Quiz

### Look at the series, determine the pattern, and find the value of the unknown number!

A multiple-choice quiz by achernar. Estimated time: 4 mins.

Author
achernar
Time
4 mins
Type
Multiple Choice
Quiz #
171,980
Updated
Aug 15 22
# Qns
15
Difficulty
Average
Avg Score
12 / 15
Plays
74092
Awards
Top 10% Quiz
Last 3 plays: Guest 107 (10/15), Guest 31 (12/15), Ammelyn2 (12/15).
This quiz has 2 formats: you can play it as a or as shown below.
Scroll down to the bottom for the answer key.
1. 0, 1, 3, 6, 10, 15, x
Hint

21
22
19
23

#### NEXT>

2. 1, 4, 27, 256, x
Hint

3125
81
729
125

#### NEXT>

3. 1, 1, 2, 3, 5, 8, 13, 21, x
Hint

29
30
34
26

#### NEXT>

4. 1, 2, 4, 8, 16, 32, 64, 128, x

#### NEXT>

5. 1, 4, 6, 9, 11, 14, 16, 19, x
Hint

24
22
21
19

#### NEXT>

6. 3, 1, 2, 0, 1, -1, x

7. 1, 3, 5, 7, x

#### NEXT>

8. 1, 8, 27, 64, 125, 216, x
Hint

300
343
324
334

#### NEXT>

9. -1, 0, 3, 8, 15, 24, 35, 48, 63, 80, x
Hint

101
100
99
98

#### NEXT>

10. 1, -1, 2, 0, 3, x
Hint

1
-1
0
5

#### NEXT>

11. 7, 14, 21, 28, 35, x

#### NEXT>

12. 1, 2, 4, 7, 11, 16, 22, x Hint

29
25
27
28

#### NEXT>

13. 1, 8, 5, 12, 9, 16, 13, 20, x Hint

27
47
37
17

#### NEXT>

14. 1, 2, 5, 14, 41, x Hint

122
72
68
256

#### NEXT>

15. 1, 2, 3, 4, 5, 6, 7, x

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Quiz Answer Key and Fun Facts
1. 0, 1, 3, 6, 10, 15, x

In this sequence you'll notice that the difference between each pair of numbers gets incremented by 1 as you move ahead in the sequence:

1 = 0 + 1
3 = 1 + 2
6 = 3 + 3
10 = 6 + 4
15 = 10 + 5

And so the missing number in the sequence must be greater than the previous number by 6.

Therefore,
x = 15 + 6 = 21

And so the missing number is 21.
2. 1, 4, 27, 256, x

This one's slightly tricky:

In this sequence, consecutive positive integers are each raised to the power of themselves. In mathematical language, if 'n' is a positive integer, then:

n^n = a

where 'a' is a number in the sequence. Here,

1^1 = 1
2^2 = 4
3^3 = 27
4^4 = 256

And so the next number in the sequence (x) is equal to 5^5, which is 3125.
3. 1, 1, 2, 3, 5, 8, 13, 21, x

This really is my favourite sequence. :-)

Here, each number is equal to the sum of the two numbers preceding it:

2 = 1 + 1
3 = 2 + 1
5 = 3 + 2
8 = 5 + 3
13 = 8 + 5
21 = 13 + 8

The value of 'x' will hence be the sum of 21 and 13, which is 34.

This is special sequence of numbers known as the "Fibonacci Sequence". This sequence was first described by Leonardo of Pisa, a.k.a. Fibonacci, in 1200 AD, to describe the growth of rabbit-population!

I highly recommend giving it a read, it is very interesting.
4. 1, 2, 4, 8, 16, 32, 64, 128, x

Pretty straightforward: each number is exactly twice the previous number. And so 'x' should be twice of the number preceding it, which is 128:

x = 2 * 128 = 256

And hence 256 is the answer.

Another way to look at it is that each number is a consecutive power of 2:

1 = 2^0
2 = 2^1
4 = 2^2
8 = 2^3
16 = 2^4
32 = 2^5
64 = 2^6
128 = 2^7

And 256 = 2^8.
5. 1, 4, 6, 9, 11, 14, 16, 19, x

Here, 3 and 2 are alternately added to the previous number in the sequence:

1 + 3 = 4
4 + 2 = 6
6 + 3 = 9
9 + 2 = 11
11 + 3 = 14
14 + 2 = 16
16 + 3 = 19

And so the next number will be equal to 19 + 2, which is 21.
6. 3, 1, 2, 0, 1, -1, x

In this sequence you alternately subtract 2 and add 1:

3 - 2 = 1
1 + 1 = 2
2 - 2 = 0
0 + 1 = 1
1 - 2 = -1

7. 1, 3, 5, 7, x

Easy enough- consecutive odd numbers: the next odd number after 7 is 9, which is the answer.
8. 1, 8, 27, 64, 125, 216, x

This is the series of cubes of consecutive natural numbers:

1^3 = 1
2^3 = 8
3^3 = 27
4^3 = 64
5^3 = 125
6^3 = 216

And the next number is the cube of 7 (7^3), which is 343.
9. -1, 0, 3, 8, 15, 24, 35, 48, 63, 80, x

The rule here is to take 1 less than the squares of consecutive whole numbers. So if 'n' is a whole number, we take (n^2 - 1):

-1 = 0 - 1 = 0^2 - 1
0 = 1 - 1 = 1^2 - 1
3 = 4 - 1 = 2^2 - 1
8 = 9 - 1 = 3^2 - 1
15 = 16 - 1 = 4^2 - 1
24 = 25 - 1 = 5^2 - 1
35 = 36 - 1 = 6^2 - 1
48 = 49 - 1 = 7^2 - 1
63 = 64 - 1 = 8^2 - 1
80 = 81 - 1 = 9^2 - 1

And so the next number in the series should be 1 less than the square of 10.

x = 10^2 - 1
=> x = 100 - 1
=> x = 99

Hence, the value of x is 99.

This is what I had in mind while writing this question, but if you look closely, there's a much more obvious pattern that this sequence follows. I won't spoil it for you and leave it for you to find; that is, unless you have already! I have to admit I hadn't noticed it myself until a few people wrote to me about it... it's truly fascinating how the two "rules" produce the same sequence.
10. 1, -1, 2, 0, 3, x

In this sequence you alternately subtract 2 and add 3:

-1 = 1 - 2
2 = -1 + 3
0 = 2 - 2
3 = 0 + 3

And so the value of 'x' must be 2 less than that of the number directly preceding it:
x = 3 - 2 = 1
11. 7, 14, 21, 28, 35, x

In this pattern you just have consecutive multiples of 7:

7 = 7 1
14 = 7 * 2
21 = 7 * 3
28 = 7 * 4
35 = 7 * 5

The value of 'x' is (7 * 6), which is 42.
12. 1, 2, 4, 7, 11, 16, 22, x

In this sequence, the difference between two consecutive numbers goes on getting incremented by 1:

2 = 1 + 1
4 = 2 + 2
7 = 4 + 3
11 = 7 + 4
16 = 11 + 5
22 = 16 + 6

'x' will be equal to the sum of the preceding number and 7,

x = 22 + 7 = 29

Hence, the value of 'x' is 29.
13. 1, 8, 5, 12, 9, 16, 13, 20, x

Alternately add 7 and subtract 3:

1 + 7 = 8
8 - 3 = 5
5 + 7 = 12
12 - 3 = 9
9 + 7 = 16
16 - 3 = 13
13 + 7 = 20

The value of 'x' will be 3 less than 20, and so 'x' is equal to 17.
14. 1, 2, 5, 14, 41, x

Note that here the differences between consecutive numbers in the series are 1, 3, 9 and 27: consecutive powers of 3.

2 = 1 + 1 = 1 + 3^0
5 = 2 + 3 = 2 + 3^1
14 = 5 + 9 = 5 + 3^2
41 = 14 + 27 = 14 + 3^3

Now, 3^4 = 81, and so we can get the value of 'x' by adding 81 to the number preceding it:

x = 41 + 3^4
=> x = 41 + 81
=> x = 122

===
Another way of going about solving this one is to treble each number and then subtract one, in each case, the answer is the same! (Thanks to all the people who wrote in to mention this!)
15. 1, 2, 3, 4, 5, 6, 7, x

I hope you enjoyed playing this quiz!
Source: Author achernar

This quiz was reviewed by FunTrivia editor crisw before going online.
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