Number Series for Infosys Aptitude: 6 Patterns, 12 Solved Questions
6 number series pattern types with 12 solved questions from Infosys aptitude rounds. Covers SE vs SP test differences, timing strategies, and the 2026 hiring context.
Number series is the most consistent quantitative section across every Infosys aptitude paper FACE Prep has tracked. It appears in the online test for both SE and SP tracks, weighted at 5–8 questions per sitting, and drawn from six pattern types that recur year after year.
This article covers those six types, 12 solved questions across the full difficulty range, and the 2026 context, including what Infosys’s CEO said in Q4 FY26 earnings about how AI-attuned skills now affect starting compensation.
What the Infosys Online Aptitude Test Actually Covers
Infosys runs a single online assessment that gates all three hiring tracks: System Engineer (SE), Specialist Programmer (SP), and Power Programmer (PP). The quantitative section includes arithmetic, algebra, and number series questions. For the broader Infosys aptitude test, number series typically accounts for 5–8 items per sitting.
The three tracks differ in pay, coding-section weight, and shortlisting criteria:
| Track | Starting CTC | Key differentiator |
|---|---|---|
| System Engineer (SE) | ₹3.6 LPA | Bulk fresher track; standard aptitude plus tech interview |
| Specialist Programmer (SP) | ₹6.5 LPA | Heavier DSA coding section; InfyTQ certification holders preferred |
| Power Programmer (PP) | ₹9.5 LPA | HackWithInfy top performers; 7.5+ CGPA; InfyTQ required |
Number series difficulty is comparable across SE and SP. The SP test is harder because of DSA, not because the series patterns change. Clear the number series section fast and save time for the coding problems.
The 6 Number Series Pattern Types
The overwhelming majority of Infosys number series questions fall into one of these six categories. The practice problems in the next section are tagged to each type.
1. Arithmetic (constant difference) Each term changes by a fixed amount. The difference between consecutive terms is constant. Example: 4, 9, 14, 19, 24, ? (constant difference: +5; answer: 29)
2. Geometric (constant ratio) Each term is multiplied or divided by a fixed number. Example: 3, 6, 12, 24, 48, ? (ratio: ×2; answer: 96)
3. Square or cube series Terms are perfect squares or cubes of consecutive integers, sometimes with an offset. Example: 1, 8, 27, 64, 125, ? (the terms are 1³, 2³, 3³, 4³, 5³; answer: 216, which is 6³)
4. Prime number series Terms are consecutive prime numbers, sometimes in a modified form. Example: 2, 3, 5, 7, 11, ? (consecutive primes; answer: 13)
5. Fibonacci and sum-based series Each term equals the sum of the two preceding terms (or a variation: sum of three, alternating additions). Example: 1, 1, 2, 3, 5, 8, ? (each term equals the sum of the previous two; answer: 13)
6. Alternating or two-interleaved series Two separate series are interleaved. Even-position terms follow one rule; odd-position terms follow another. This is the type that trips candidates most often. Example: 2, 4, 8, 7, 14, 28, 27, ? (odd-position and even-position terms follow separate patterns; answer: 54)
12 Solved Practice Questions
Each question is tagged with its pattern type. Work through the pattern before reading the answer.
Q1. Find the missing number: 2, 5, 10, 17, 26, ?
Options: A) 37 B) 36 C) 38 D) 40
Pattern: Arithmetic (differences increase by odd numbers: +3, +5, +7, +9, +11) 26 + 11 = 37 Answer: A
Q2. Find the next term: 100, 96, 92, 88, ?
Options: A) 80 B) 84 C) 85 D) 82
Pattern: Arithmetic (constant difference of -4) 88 - 4 = 84 Answer: B
Q3. What comes next: 1, 8, 27, 64, 125, ?
Options: A) 150 B) 216 C) 343 D) 512
Pattern: Cube series (1³, 2³, 3³, 4³, 5³) 6³ = 216 Answer: B
Q4. Identify the missing term: 7, 10, 16, 28, ?
Options: A) 34 B) 46 C) 52 D) 56
Pattern: Arithmetic with doubling differences (+3, +6, +12, +24) Each difference doubles the previous one: 3 × 2 = 6, 6 × 2 = 12, 12 × 2 = 24. 28 + 24 = 52 Answer: C
Q5. Find the next number in the prime series: 2, 3, 5, 7, 11, ?
Options: A) 12 B) 15 C) 13 D) 17
Pattern: Prime series Next prime after 11 is 13 Answer: C
Q6. What is the missing term: 0, 1, 1, 2, 3, 5, 8, ?
Options: A) 11 B) 13 C) 12 D) 14
Pattern: Fibonacci (each term = sum of previous two) 5 + 8 = 13 Answer: B
Q7. Find the missing number: 4, 16, 36, 64, 100, ?
Options: A) 121 B) 144 C) 136 D) 196
Pattern: Squares of even numbers (2², 4², 6², 8², 10²) 12² = 144 Answer: B
Q8. What comes next: 3, 6, 18, 72, ?
Options: A) 144 B) 216 C) 288 D) 360
Pattern: Geometric with increasing multiplier (×2, ×3, ×4) 72 × 4 = 288 Answer: C
Q9. Find the next term: 5, 11, 23, 47, 95, ?
Options: A) 188 B) 190 C) 191 D) 192
Pattern: Each term = previous × 2 + 1 95 × 2 + 1 = 191 Answer: C
Q10. Find the missing number: 144, 121, 100, 81, 64, ?
Options: A) 49 B) 36 C) 25 D) 47
Pattern: Descending square series (12², 11², 10², 9², 8², 7²) 7² = 49 Answer: A
Q11. What is the next term: 2, 4, 12, 48, 240, ?
Options: A) 480 B) 960 C) 1440 D) 720
Pattern: Multiply by increasing integers (×2, ×3, ×4, ×5, ×6) 240 × 6 = 1440 Answer: C
Q12. Find the missing term: 6, 13, 27, 55, ?
Options: A) 101 B) 110 C) 111 D) 112
Pattern: Each term = previous × 2 + 1 55 × 2 + 1 = 111 Answer: C
Solving Strategies for the Infosys Timed Test
The Infosys online test runs under real time pressure. Here is what works in practice.
Calculate first-order differences first. Subtract term 2 from term 1, term 3 from term 2, and so on. If those differences are constant, you have arithmetic. If the differences themselves follow a pattern (doubling, halving, or increasing by a fixed step), you have a second-order series. This diagnostic takes 15 seconds and eliminates guessing.
Check for squares and cubes when numbers jump fast. If consecutive terms look like 1, 4, 9, 16 or 1, 8, 27, 64, check the square or cube of the implied integer before anything else.
For alternating series, separate odd and even positions. Write positions 1, 3, 5, 7 in one row and positions 2, 4, 6, 8 in another. Each row is usually a simpler series by itself. The alternating type trips candidates because they try to find a single rule across all terms.
Use option elimination at the 30-second mark. Substitute each answer choice back into the series and check which one fits the pattern. In a 4-option MCQ, this takes 30–45 seconds and is faster than hunting for a pattern cold.
Do not spend more than 90 seconds on any single question. The logical reasoning section and verbal sections both need time. Mark and move; return if time permits.
The 2026 Infosys Hiring Context
Infosys onboarded 20,000 freshers in FY26 and plans the same volume in FY27, according to CEO Salil Parekh’s Q4 FY26 earnings commentary (Financial Express, FY26). That volume matters for students watching campus placement cycles.
What also matters: Parekh explicitly noted that Infosys now has different starting compensation for candidates with skills more attuned to AI. The company is also building what he called a “forward-deployed engineer” pool to do AI solution work directly with clients. This signals that the SE/SP/PP differentiation will tighten further as AI-readiness becomes a visible sorting criterion alongside aptitude scores.
Passing number series quickly gets you through the aptitude gate. But which track you land on after the gate depends on what else you bring.
Students who can demonstrate deployed AI work before their final-year placement window are better positioned for Infosys’s forward-deployed engineering roles. TinkerLLM (₹299) covers LLM fundamentals: API calls, prompt structure, and RAG basics, delivered in a self-paced playground format. That is the practical entry point if you want a working project in your portfolio before the placement cycle opens.
If you’re targeting the SP and PP track bands or client-facing AI solution roles, the 2026 AI roadmap for Indian engineering students lays out the full curriculum path: what to build, in what order, and how production AI engineering differs from the aptitude prep you’re doing now.
Aptitude is the floor. AI-readiness is becoming the ceiling filter.
Primary sources
Frequently asked questions
How many number series questions appear in the Infosys online aptitude test?
Typically 5–8 questions in the quantitative section, though the exact count varies by test version. FACE Prep has tracked this across papers from 2021 to 2025.
Is the number series difficulty different for SE and SP tracks?
The number series difficulty is roughly similar across SE and SP. The SP online test differs mainly in its coding section, which is heavier and more DSA-focused.
How do I quickly find the pattern in an unfamiliar number series?
Calculate the first-order differences (term 2 minus term 1, term 3 minus term 2, and so on). If those are constant, it is arithmetic. If the differences themselves follow a pattern, you have a second-order or alternating series.
Does Infosys repeat number series questions from previous years?
Question banks rotate, so exact repeats are rare. Pattern types repeat consistently: arithmetic progressions and difference-doubling patterns appear in nearly every paper.
How much time should I spend per number series question in the test?
Budget 60–75 seconds per question. If you do not spot the pattern within 30 seconds, use option elimination — substitute each answer choice back into the series and check which one fits.
Does InfyTQ certification help with Infosys placement selection?
Yes. InfyTQ certification holders are preferred for shortlisting in the SP track. The PP track (₹9.5 LPA) is restricted primarily to top HackWithInfy performers and InfyTQ-certified students with 7.5+ CGPA.
A self-paced playground for building with LLMs.
TinkerLLM is FACE Prep's sister property. A guided environment for shipping real LLM applications, the kind of project that earns a paragraph on your resume, not a line.
Try TinkerLLM (₹299 launch)