Logical Reasoning - Number Series - Discussion
Discussion Forum : Number Series - Type 1 (Q.No. 19)
Directions to Solve
In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much
19.
Look at this series: 8, 6, 9, 23, 87 , ... What number should come next?
Answer: Option
Explanation:
8 x 1 - 2 = 6
6 x 2 - 3 = 9
9 x 3 - 4 = 23
23 x 4 - 5 = 87
87 x 5 - 6 = 429 ...
Discussion:
129 comments Page 4 of 13.
Sun said:
2 years ago
Thank you everyone for explaining the answer.
(2)
Sathwika reddy said:
12 months ago
It was a good explanation. Thanks all.
(2)
Manoj said:
12 months ago
Very helpful. Good to practice. Thanks.
(2)
Aadarsh Yadav said:
11 months ago
The series logic starts with the pattern: 6, 9, 23, 87.
(2)
Saikishor said:
5 months ago
Good explanation. Thanks all.
(2)
Suri said:
4 months ago
429 is the correct answer.
(2)
The Helpful Brit said:
1 decade ago
General form is X(n+1) = (X (n)*n) - (n+1) ). Where X(n) is the term number in the series, X (n+1) is the subsequent term and n is the element position aka as index.
All algebraic terms will always represent integer values.
X(n); n(X (n)*n)-(n+1)) = X(n+1).
X(1) = 8; n = 1((8)*(1))-(2)) = 6.
X(2) = 6; n = 2((6)*(2))-(3)) = 9.
X(3) = 9; n = 3((9)*(3))-(4)) = 23.
X(4) = 23; n = 4((23)*(4))-(5)) = 87.
X(5) = 87; n = 5((87)*(5))-(6)) = 429.
Therefore.
X(6) = 429; n = 6((429)*(6))-(7)) = 2567.
All algebraic terms will always represent integer values.
X(n); n(X (n)*n)-(n+1)) = X(n+1).
X(1) = 8; n = 1((8)*(1))-(2)) = 6.
X(2) = 6; n = 2((6)*(2))-(3)) = 9.
X(3) = 9; n = 3((9)*(3))-(4)) = 23.
X(4) = 23; n = 4((23)*(4))-(5)) = 87.
X(5) = 87; n = 5((87)*(5))-(6)) = 429.
Therefore.
X(6) = 429; n = 6((429)*(6))-(7)) = 2567.
(1)
Varaprasad said:
1 decade ago
Only this question is thinkable one while compare to others.
(1)
Aayush said:
6 years ago
Solution : 8 x 1 - 2 = 6,
6 x 2 - 3 = 9,
9 x 3 - 4 = 23,
23 x 4 - 5 = 87,
87 x 5 - 6 = 429.
6 x 2 - 3 = 9,
9 x 3 - 4 = 23,
23 x 4 - 5 = 87,
87 x 5 - 6 = 429.
(1)
Akshara said:
5 years ago
You can understand this problem by understanding the relation between 9, 23 as shown in the solution 9'-3-4=23, and later you check the remaining numbers by using this method.
If it suitable for every number before 9 then you can do this with 87.
If it suitable for every number before 9 then you can do this with 87.
(1)
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