UPSC CSE Prelims 2026 CSAT: Every expert advices that the CSAT paper must be taken seriously, and aspirants should begin practising daily from now until the exam. In our latest edition of the UPSC CSAT Simplified series, expert Dr Mansoor Agha Siddiqui first decoded the nature and structure of the CSAT paper (click here). The second part focused on tackling comprehension (click here), a section that often consumes valuable exam time. The third part examined logical reasoning and analytical ability questions in CSAT paper, helping build a strong conceptual foundation (click here). The fourth part explained General Mental Ability questions in CSAT (click here).In the fifth part today, Dr Siddiqui turns to Basic Numeracy and Data Interpretation.Subscribe | UPSC Essentials of The Indian Express to stay ahead in your Civil Services preparation with focused, exam-relevant insights.About our expert: For UPSC aspirants grappling with the challenges of CSAT, Dr. Mansoor Agha Siddiqui brings decades of experience to the conversation. With over three decades of guiding students through aptitude and assessment tests such as GMAT, IIM-CAT, GRE, SAT, LSAT, CUET and others, he has worked extensively with the design and demands of aptitude-based examinations. His expertise also includes mentoring UPSC aspirants across multiple areas, including CSAT, making his insights particularly relevant for candidates preparing for this crucial paper.CSAT SIMPLIFIED: Click for Part 1 | Click for Part 2 | Click for Part 3 | Click for Part 4 Part 5 : Basic Numeracy and Data Interpretation for CSATAs the fourth topic in our series, Basic Numeracy and Data Interpretation covers concepts related to numbers and their relationships, order of magnitude, and data interpretation. The latter includes questions based on data analysis, where information may be presented in various forms such as tables, graphs, and charts. It also includes Data Sufficiency, which requires assessing whether the given data is adequate to answer a question. Overall, this section measures numerical ability and accuracy in mathematical calculations.The questions range from purely numeric calculations to problems of arithmetical reasoning, graph and table reading, percentage analysis and quantitative analysis. In this we require more reasoning ability to solve mathematical problems than pure mathematics itself. As a whole the students are tested for their sharpness to analyze the given data in a short span of time.Story continues below this adLet’s first look at the different sections in this topic of CSAT and what you should know before attempting questions.Basic Numeracy Section in CSATThis section can be divided into five modules, as given below:1. Numbers and their properties: It includes basic knowledge of various types of numbers such as rational, irrational numbers, prime numbers, and their properties etc., Surds and Indices, Logarithms, Simplification questions based on BODMAS and basic formulas, HCF and LCM, remainders, divisibility tests, Unit Digit etc.The questions related to BODMAS, Surds and Indices, Logarithms, Divisibility Rules, and HCF & LCM are the most important, so the students are advices to do a lot of practice of these questions.Story continues below this ad2. Arithmetic: In this module topics like percentage and its properties (Simple & Compound Interest), Ratio & Proportion and its properties (Partnership and Mixtures), Time Speed & Distance (Including concept of trains, boats & streams, and clocks) and Time and Work which also covers questions on Pipes and Cisterns are present.Questions in this module are more scoring than rest of the others modules as they are easy to interpret and also there are very few concepts that one has to master to do well in these topics.3. Algebra: This module contains Basics of polynomials, Linear equations on 2/3 variables, quadratic equations and Progressions (AP, GP & HP), Basics of Maxima & Minima.Till now algebra has not been asked in the General Mental Ability Section in the previous years, but still students are advised to go through the basic concepts of algebra.Story continues below this ad4. Geometry: In geometry we have topics like basics of line, angles, triangles, quadrilateral, circles & their properties, area, and perimeter of various figures like triangle, quadrilateral, circle etc. and volume of figures like cylinder, cone, sphere, hemisphere etc.Geometry questions have been asked in the previous year papers, so students should go through the basics theorems and the formulae to find the area and the volume of different figures. Questions where one has to find the shaded area are the most important from this module.5. Modern Maths: It has topics like Permutation & Combinations, Probability, and the basic logical aspect of set theory. Permutation and Combination is a very important topic from this module as in the past, every year one or two questions of moderate to high difficulty level were asked from this topic.Data Interpretation Section in CSATThe Data Interpretation part has questions based on data represented in the form of tables, bar graphs, line graphs, pie charts, combinational graphs etc and students are required to analyze the data and solve the questions in context to the data given.Story continues below this adWe basically have three types of questions in the Data interpretation i.e. calculation, counting and reasoning-based questions.In calculation based questions we have to do mathematical calculations to find the answer.In counting based we have to do counting while following certain constraints.In reasoning-based questions more than one constraint is given to solve the question asked.Data Sufficiency Part in CSATIn Data Sufficiency, a question followed by two statements and you will be expected to answer whether the information provided in the individual statements or collectively is sufficient to answer the question. The mathematical knowledge and skill required to solve Data Sufficiency problems is no greater than that required to solve standard aptitude problems. What make Data Sufficiency problems appear more difficult at first are the complicated directions. But once one becomes familiar with the directions, one finds these problems no harder than standard aptitude problems.Also, Data Sufficiency problems give a lot of scope of elimination of options, so these problems are worth attempting.Data sufficiency questions are based on the same topics that one has studied in Basic Numeracy.Story continues below this adThere can also be reasoning based questions on Data Sufficiency like the one released by UPSC in the sample papers and in previous exams.CSAT PRACTICE QUESTIONS Let us analyse a few Basic Numeracy & Data Interpretation.Question 1:A person has to cover a distance of 6 km in 45 minutes. If he covers one-half of the distance in two-thirds of the total time; to cover the remaining distance in the remaining time, his speed (in km/hr.) must be:(a) 6(b) 8(c) 12(d) 15Answer: (c)Explanation:Remaining distance = 3 km and Remaining time = (1/3 x 4) min.= 15 min = 1/4 hourTherefore, Required speed = (3 x 4) km/hr. = 12 km/hr. Question 2:Story continues below this adA, B and C are on a trip by a car. A drives during the first hour at an average speed of 50 km/hr. B drives during the next 2 hours at an average speed of 48 km/hr. C drives for the next 3 hours at an average speed of 52 km/hr. They reached their destination after exactly 6 hours. Their mean speed was:(a) 50 km/hr(b) 50 (1/3) km/hr(c) 51 (1/3) km/hr(d) 52 km/hrAnswer: (c) Question 3:A dishonest milkman professes to sell his milk at cost price but he mixes it with water and thereby gains 25%. The percentage of water in the mixture is :(a) 4%(b) 6 (1/4)%(c) 20%(d) 25%Answer: (c)Explanation:Let C.P. of 1 litre milk be Re. 1.Then, S.P. of 1 litre of mixture = Re. 1, Gain = 25%.C.P. of 1 litre mixture = Re. (100/125 x 1) = Re 4/5 Question 4:Four persons are chosen at random from a group of 3 men, 2 women and 4 children. The chance that exactly 2 of them are children, is:(a) 1/9(b) 1/5(c) 1/12(d) 10/21Answer: (d)Explanation: Let S be the sample space and E be the event of choosing four persons such that 2 of them are children. Then, Question 5:Story continues below this adThe length of a blackboard is 8 cm more than its breadth. If the length is increased by 7 cm and breadth is decreased by 4 cm, the area remains the same. The length and breadth of the blackboard (in cm) will be:(a) 28, 20(b) 34, 26(c) 40, 32(d) 56, 48Answer: (a)Explanation:Let breadth = x cm. Then, length = (x + 8) cm.So, length = 28 cm and breadth = 20 cm. Direction for Question no. 6: The bar-graph given below shows the percentage distribution of total expenditures of a Company under various expense heads during 2003. Study the graph and answer the questions that follow:Percentage Distribution of Total Expenditures of a CompanyQuestion 6:The expenditure on the interest on loans is by what percent more than the expenditures on transport?(a) 5%(b) 10%(c) 20%(d) 40%Answer: (d)Explanation:Let the total amount of expenditures be Rs. x.Next Article in CSAT Simplified: Introduction to basic numeracy for CSATShare your views and suggestions in the comment box or at manas.srivastava@indianexpress.comSubscribe to our UPSC newsletter. Stay updated with the latest UPSC articles by joining our Telegram channel – IndianExpress UPSC Hub, and follow us on Instagram and X. Click Here to read the UPSC Essentials magazine for March 2026.