In the number sequence 0, 10, 1110, 3110, 132110, each term is generated by describing the digits of the previous term. What is the next term that should replace the question mark in this sequence?

Difficulty: Medium

Correct Answer: 1113122110

Explanation:


Introduction / Context:
This question is another variation of the look-and-say style sequence, but here the pattern starts from 0: 0, 10, 1110, 3110, 132110, and so on. The idea is that each term is obtained by reading off the previous term as counts of identical digits and then writing those counts and digits as a new number. The problem checks whether you can correctly identify the groups of digits in 132110 and then encode that description into the next term.


Given Data / Assumptions:

  • The sequence given is: 0, 10, 1110, 3110, 132110.
  • Each term is formed by "describing" the previous term in terms of runs of identical digits.
  • We must find the term that follows 132110.
  • The answer must be chosen from the provided options, which are all long digit strings.
  • We assume there is no hidden arithmetic beyond counting groups of digits.


Concept / Approach:
For each term, we group consecutive identical digits in the previous term and then write down the count followed by the digit. For example, starting from 0, there is "one 0", which becomes 10. From 10, there is "one 1, one 0", which becomes 1110. From 1110, we get "three 1s, one 0", which becomes 3110, and so on. We apply this same rule to 132110 to generate the next term.


Step-by-Step Solution:
Step 1: Write the last known term clearly: 132110.Step 2: Group consecutive digits: the digits appear as 1, 3, 2, 1, 1, 0. The runs are: "one 1", "one 3", "one 2", "two 1s", "one 0".Step 3: Convert each run into a count followed by the digit: "one 1" becomes 11, "one 3" becomes 13, "one 2" becomes 12, "two 1s" becomes 21, and "one 0" becomes 10.Step 4: Write these parts in order: 11, 13, 12, 21, 10.Step 5: Concatenate them into a single number: 11 13 12 21 10 = 1113122110.


Verification / Alternative check:
To confirm that the same rule has been consistently applied, you can recheck earlier terms. From 3110, the groups are "one 3", "two 1s", "one 0", which gives 132110. That matches the given sequence. Applying the same grouping-and-describing method to 132110 naturally yields 1113122110, confirming that the pattern has been followed correctly.


Why Other Options Are Wrong:
Option 311322110 misorders the counts and digits, mixing the structure. Option 33122110 suggests there are three 3s or misreads the groups of 1s and 2s, which is incorrect. Option 13222110 incorrectly counts the number of each digit. Only option 1113122110 correctly represents "one 1, one 3, one 2, two 1s, one 0" from the term 132110.


Common Pitfalls:
Students often misgroup digits, especially when there are multiple single digits in a row, or they try to treat the sequence as an arithmetic or geometric progression rather than a descriptive sequence. Another common error is to miscount the number of repeated digits in the middle of the term. Carefully scanning from left to right, grouping identical digits, and then writing the count followed by the digit helps avoid these mistakes.


Final Answer:
The correct next term in the sequence is 1113122110.

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