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Sequence Completion (Missing Term)

Sequence Completion problems present a sequence with one or more missing terms indicated by a blank or question mark. You must identify the pattern and determine the missing term(s). These problems test your ability to find patterns even when terms are not consecutive.

10Worksheets
200+Practice Questions
IntermediateDifficulty
2-3 hoursHours to Master

What You'll Learn

Introduction & Overview Why This Matters How to Solve Pro Tips & Tricks
Shortcut Methods Common Mistakes Practice Worksheets Exam Importance

Introduction to Sequence Completion (Missing Term)

Sequence Completion problems present a sequence with one or more missing terms indicated by a blank or question mark. You must identify the pattern and determine the missing term(s). These problems test your ability to find patterns even when terms are not consecutive.

Prerequisites

Arithmetic progression concepts Geometric progression concepts Fibonacci pattern recognition Pattern extrapolation
Why This Matters: Missing Term problems appear in 2-3 questions in SSC CGL and Banking PO exams. They test pattern recognition with gaps.

How to Solve Sequence Completion (Missing Term) Problems

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Step 1: Identify the positions of known terms and the missing term

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Step 2: Find the pattern using terms before and after the missing term

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Step 3: For AP: missing = (term_before + term_after) / 2 (if equidistant)

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Step 4: For GP: missing = √(term_before × term_after) (if equidistant)

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Step 5: Use nth term formula to find missing term at position n

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Step 6: Verify the pattern works for all given terms

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Step 7: Present the missing term

Pro Strategy: If the missing term is in the middle, find the pattern using surrounding terms. For AP, the middle term is the average of its neighbors. For GP, it's the geometric mean.

Example Problem

Example: Find the missing term: 5, 9, 13, ?, 21, 25 Solution: Step 1: AP with common difference d = 9-5 = 4 Step 2: Check: 13+4=17, 17+4=21 ✓ Step 3: Missing term = 17 Answer: 17

Pro Tips & Tricks

  • For AP missing middle term: a_missing = (a_left + a_right)/2
  • For GP missing middle term: a_missing = √(a_left × a_right)
  • For Fibonacci: each term is sum of two preceding
  • If multiple terms missing, find pattern using known pairs
  • The pattern may be constant difference, ratio, or alternating
  • Use position numbers to find formula: aₙ = a₁ + (n-1)d

Shortcut Methods to Solve Faster

AP: missing = (left + right) / 2
GP: missing = √(left × right)
If difference is constant, missing = left + d
If ratio is constant, missing = left × r

Common Mistakes to Avoid

Assuming pattern type without verifying
Using wrong formula for missing term position
Not checking if the pattern works for all terms
Forgetting that multiple patterns might fit limited data

Exam Importance

Sequence Completion (Missing Term) is an important topic for various competitive exams. Here's how frequently it appears:

SSC CGL
2-3 questions
BANKING PO
2-3 questions
RAILWAYS RRB
2-3 questions
CAT
1-2 questions
INSURANCE
2-3 questions

Ready to Master Sequence Completion (Missing Term)?

Start with Worksheet 1 and work your way up to expert level! Each worksheet includes:

20 practice questions
Detailed solutions
Step-by-step explanations
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