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Number-Letter Alternating

Number-Letter Alternating series problems present sequences where numbers and letters occupy alternating positions (e.g., A1, C3, E5, G7). The numbers and letters each follow their own independent pattern. You must identify both patterns and determine the next term in the series.

10Worksheets
200+Practice Questions
BeginnerDifficulty
1-2 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 Number-Letter Alternating

Number-Letter Alternating series problems present sequences where numbers and letters occupy alternating positions (e.g., A1, C3, E5, G7). The numbers and letters each follow their own independent pattern. You must identify both patterns and determine the next term in the series.

Prerequisites

Alphabet positions (A=1 to Z=26) Basic arithmetic progressions Pattern recognition in alternating sequences Understanding of term positions (odd/even)
Why This Matters: Number-Letter Alternating problems are the most common mixed series type. You can expect 2-3 questions in SSC CGL, 2-3 in Banking PO, and 2-3 in Railways RRB exams.

How to Solve Number-Letter Alternating Problems

1

Step 1: Separate the series into two subsequences based on position parity (odd positions and even positions)

2

Step 2: Analyze the letter subsequence pattern (e.g., A→C→E→G: +2 each time)

3

Step 3: Analyze the number subsequence pattern (e.g., 1→3→5→7: +2 each time)

4

Step 4: Determine which type (letter or number) the next term will be based on its position

5

Step 5: Apply the appropriate pattern to find the next letter or number

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Step 6: Combine the letter and number to form the next term

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Step 7: Verify the pattern holds for all given terms

Pro Strategy: Always separate letters and numbers into independent sequences. Analyze each subsequence separately. The next term's type is determined by its position in the alternating pattern.

Example Problem

Example: Find the next term in the series: A1, C3, E5, G7, ___ Solution: Step 1: Odd positions (1st,3rd,5th): A, C, E, G (letters); Even positions (2nd,4th): 1,3,5,7 (numbers) Step 2: Letter pattern: A(1)→C(3)→E(5)→G(7): +2 each time Step 3: Number pattern: 1→3→5→7: +2 each time Step 4: Next is 5th term (odd position) → letter Step 5: Next letter = G(7) + 2 = 9 → I Step 6: Next term = I9 Answer: I9

Pro Tips & Tricks

  • Odd positions often contain letters, even positions contain numbers (or vice versa)
  • Letter patterns typically involve arithmetic progression in alphabet positions
  • Number patterns typically involve arithmetic progression
  • The step size may be different for letters and numbers
  • Common step sizes: +1, +2, +3, -1, -2, -3
  • Write the series with position numbers (1st, 2nd, 3rd...) for clarity

Shortcut Methods to Solve Faster

If letters increase by +2 and numbers increase by +2, the pattern is consistent
For letters: next letter = current letter position + step
For numbers: next number = current number + step
The term at position n is letter if n is odd, number if n is even (or opposite)

Common Mistakes to Avoid

Not separating letters and numbers into independent sequences
Assuming the same pattern applies to both letters and numbers
Misidentifying which position comes next
Forgetting to convert letters to position numbers for pattern analysis

Exam Importance

Number-Letter Alternating 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
0-1 questions
INSURANCE
2-3 questions

Ready to Master Number-Letter Alternating?

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

20 practice questions
Detailed solutions
Step-by-step explanations
Start Practicing Now