20 questions UPSC asked between 2016 and 2026, 30 minutes, negative marking — your score as soon as you submit.
Pick up where you left off
20
questions
30 min
at the exam's pace
50
maximum marks
Number system has 7 sets of about 20 questions — together, every question UPSC has asked on it since 2016. This is set 5; when you finish, the next one is a tap away.
1Answer in any order: skip, mark for review and come back from the question palette.
2Submit when you're done, or the 30 min timer submits for you. Close the page and come back any time — your answers are saved in this browser.
3See your score straight away. Sign up free (or log in) for the full report and every question with UPSC's answer and a step-by-step solution.
Marking, as in the exam: +2.5 for a correct answer, −0.83 for a wrong one, 0 if you leave it. CSAT is qualifying: 33%.
Questions from the latest paper are scored against UPSC's provisional answer key (the final key comes out after the final result).
What's in this test
Year
Questions
Easy
Medium
Hard
2026
2
1
1
0
2025
3
3
0
0
2024
2
2
0
0
2023
3
1
2
0
2022
2
0
2
0
2021
1
0
1
0
2020
3
1
2
0
2019
2
2
0
0
2017
1
1
0
0
2016
1
1
0
0
Difficulty is the Vault's own rating of each question; subjects and topics follow the official syllabus.
The timer starts when you press Start. Your progress is saved in this browser.
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About this test
How is this test marked?
As in UPSC's CSAT (GS Paper II): 2.5 marks for each correct answer and a third of that (0.83) deducted for each wrong one. A question you leave scores nothing. The maximum here is 50.
How long do I get?
30 minutes — the exam's pace (80 questions in 2 hours) for 20 questions. When the time runs out, your answers are submitted as they stand.
How are the sets made?
Every question UPSC has asked on Number system since 2016 is in one of the 7 sets of about 20, each mixing years (a passage always comes with all its questions). Questions UPSC dropped from evaluation are left out. Take them in any order; the sets page shows which you've done.
Is it free?
Yes. Anyone can take the test and see their score straight away. A free sign-up shows the full report and every question with UPSC's answer and a step-by-step solution.
Three variables x, y and z take values 2, 3, 4 or 5 such that their values are always distinct. If M and N denote the largest possible value and the smallest possible value, respectively, for the expression {(x × y) + z}; then M − N is
Question 2 of 20 · CSAT 2026, Q68
There are three types of rectangular tiles: 3′ × 3′, 3′ × 7′ and 3′ × 11′. An area of rectangular shape of dimensions 3′ × 100′ is to be covered using these tiles without breaking them. If x and y are the maximum and minimum numbers of tiles of various sizes, respectively, that can be used to cover the area exactly, then x − y is
Question 3 of 20 · CSAT 2025, Q26
If 4 ≤ x ≤ 8 and 2 ≤ y ≤ 7, then what is the ratio of maximum value of (x + y) to minimum value of (x − y)?
Question 4 of 20 · CSAT 2025, Q47
Let P = QQQ be a 3-digit number. What is the HCF of P and 481?
Question 5 of 20 · CSAT 2025, Q79
Let x be a real number between 0 and 1. Which of the following statements is/are correct?
I.x² > x³.
II.x > √x.
Select the correct answer using the code given below:
Question 6 of 20 · CSAT 2024, Q19
A can X contains 399 litres of petrol and a can Y contains 532 litres of diesel. They are to be bottled in bottles of equal size so that whole of petrol and diesel would be separately bottled. The bottle capacity in terms of litres is an integer. How many different bottle sizes are possible?
Question 7 of 20 · CSAT 2024, Q54
32⁵ + 2²⁷ is divisible by
Question 8 of 20 · CSAT 2023, Q14
Three of the five positive integers p, q, r, s, t are even and two of them are odd (not necessarily in order). Consider the following:
1.p + q + r − s − t is definitely even.
2.2p + q + 2r − 2s + t is definitely odd.
Which of the above statements is/are correct?
Question 9 of 20 · CSAT 2023, Q28
Each digit of a 9-digit number is 1. It is multiplied by itself. What is the sum of the digits of the resulting number?
Question 10 of 20 · CSAT 2023, Q69
There are large number of silver coins weighing 2 gm, 5 gm, 10 gm, 25 gm, 50 gm each. Consider the following statements:
1.To buy 78 gm of coins one must buy at least 7 coins.
2.To weigh 78 gm using these coins one can use less than 7 coins.
Which of the statements given above is/are correct?
Question 11 of 20 · CSAT 2022, Q47
A person X wants to distribute some pens among six children A, B, C, D, E and F. Suppose A gets twice the number of pens received by B, three times that of C, four times that of D, five times that of E and six times that of F. What is the minimum number of pens X should buy so that the number of pens each one gets is an even number?
Question 12 of 20 · CSAT 2022, Q75
What is the value of X in the sequence 2, 12, 36, 80, 150, X?
Question 13 of 20 · CSAT 2021, Q60
Consider the following multiplication problem:
(PQ) × 3 = RQQ, where P, Q and R are different digits and R ≠ 0.
What is the value of (P + R) ÷ Q?
Question 14 of 20 · CSAT 2020, Q9
Let p, q, r and s be natural numbers such that
p − 2016 = q + 2017 = r − 2018 = s + 2019
Which one of the following is the largest natural number?
Question 15 of 20 · CSAT 2020, Q37
How many integers are there between 1 and 100 which have 4 as a digit but are not divisible by 4?
Question 16 of 20 · CSAT 2020, Q75
How many pairs of natural numbers are there such that the difference of whose squares is 63?
Question 17 of 20 · CSAT 2019, Q37
If x is greater than or equal to 25 and y is less than or equal to 40, then which one of the following is always correct?
Question 18 of 20 · CSAT 2019, Q74
If $ means ‘divided by’; @ means ‘multiplied by’; # means ‘minus’, then the value of 10#5@1$5 is
Question 19 of 20 · CSAT 2017, Q35
There are thirteen 2-digit consecutive odd numbers. If 39 is the mean of the first five such numbers, then what is the mean of all the thirteen numbers?
Question 20 of 20 · CSAT 2016, Q13
There are five hobby clubs in a college — photography, yachting, chess, electronics and gardening. The gardening group meets every second day, the electronics group meets every third day, the chess group meets every fourth day, the yachting group meets every fifth day and the photography group meets every sixth day. How many times do all the five groups meet on the same day within 180 days?
Keyboard: A–D to choose, ←→ to move, M to mark for review.
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