Home › UPSC › CSAT - Number Series

CSAT - Number Series — UPSC Questions & Practice

Practise 683 CSAT - Number Series questions from UPSC for competitive exams such as UPSC, Banking, SSC and Railway. Read the worked questions below, check every answer with an explanation, and track what you get wrong.

Practise this topic

683 questions · 0 quizzes · free to start

Practice questions on CSAT - Number Series — with answers

Try each question first, then open the answer. Explanations are included.

1. Find the next number in the series: 3, 6, 11, 18, 27, ?

Show answer

Answer: D

Differences between terms are 3,5,7,9,11 (increasing odd numbers). Next term=27+11=38.

2. Find the next number in the series: 2, 5, 10, 17, 26, ?

Show answer

Answer: A

Differences are 3,5,7,9,11 (odd numbers increasing by 2). Next difference=11: 26+11=37.

3. Find the next number in the series: 2, 6, 12, 20, 30, ?

Show answer

Answer: D

This is the series n(n+1): 1×2,2×3,3×4,4×5,5×6,6×7. Next term=6×7=42.

4. Find the next number in the series: 1, 3, 6, 10, 15, ?

Show answer

Answer: C

These are triangular numbers, where differences increase by 1 each time (2,3,4,5,6): 15+6=21.

5. Find the next number in the series: 4, 7, 12, 19, 28, ?

Show answer

Answer: B

Differences are 3,5,7,9,11 (odd numbers). Next difference=11: 28+11=39.

Practise more CSAT - Number Series questions

More UPSC topics

CSAT - Quantitative Aptitude (1371)Indian Economy - Budget and Fiscal Policy (981)Indian Economy - GDP and National Income (688)CSAT - Simple Interest (465)CSAT - Percentage (391)Indian Economy - External Sector (372)CSAT - Ranking and Order (325)Indian Economy - National Income (279)Indian Economy - Inflation (260)CSAT - Blood Relations and Ages (232)CSAT - Ratio and Proportion (173)CSAT - Coding-Decoding (116)CSAT - Reasoning (81)CSAT - Averages (79)CSAT - Direction Sense (75)International Relations (67)Indian Polity (63)Ethics and Integrity (GS Paper IV) (62)All UPSC →