Which Number Comes Next In This Series of Numbers

Question :

1
11
21
1211
111221
312211
<— Which number comes next in this series of numbers ?

[ Try your Best before Scroll down for the answer ]

Answer :

13112221

How is the answer derived ?

The series of numbers is a description of the previous number series,

Series 1 (Line 1) is the start of the series with the number 1.

Series 2 (Line 2) describes the previous series (Line 1).
Since there is only One numeric number 1, hence to describe it in english would be “One numeric 1“,
and written as “11“.

Series 3 (Line 3) describes the previous series (Line 2).
Line 2 consists of Two numeric number 1, hence to describe it in english would be “Two numeric 1“,
and written as “21“.

Series 4 (Line 4) describes the previous series (Line 3).
Line 3 consists of Numeric number 2 followed by Numeric number 1,
Hence to describe it in english would be “One numeric 2 and One numeric 1“, and written as “1211“.

Series 5 (Line 5) describes the previous series (Line 4).
Hence to describe it in english would be “One numeric 1, One numeric 2 and Two numeric 1“,
and written as “111221“.

Series 6 (Line 6) describes the previous series (Line 5).
Hence to describe it in english would be “Three numeric 1, Two numeric 2 and One numeric 1“,
and written as “312211“.

And following the pattern, we would obtain the answer as “13112221”.

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