Question 1
If P = +, Q = −, R = ×, S = ÷, then insert the proper notations between the successive numbers in the equation 60_15_3_20_4 = 20:
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Correct AnswerB
Explanation
QRPS gives 60−15×3+20÷4=20.
LOGICAL REASONING
Mathematical Operations — UPSC CSAT Previous Year Questions
Practice UPSC CSAT previous year questions from 2011–2026 classified underMathematical Operations. Review the original question, four options, correct answer and explanation for every PYQ.
7Total PYQs
2011–2026Years
1Subtopics
TOPIC-WISE PYQs
Mathematical Operations
7 questions • 2011–2026
Question 2
In the expression 5 * 4 * 3 * 2 * 1, * is chosen from +, -, x each at most two times. What is the smallest non-negative value of the expression?
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Correct AnswerD
Explanation
Choose the allowed operators to obtain the smallest non-negative result; 5−4−3+2×1 = 0, so the minimum is 0.
Question 3
If a+b means a-b; a-b means a×b; a×b means a÷b; a÷b means a+b, then what is the value of 10+30-100×50÷25? (Operations are to be replaced simultaneously)
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Correct AnswerD
Explanation
Replace operations simultaneously: 10−30×100÷50+25. Applying normal precedence gives 10−60+25 = −25.
Question 4
If P means 'greater than (>)'; Q means 'less than (<)'; R means 'not greater than (≤)'; S means 'not less than (≥)' and T means 'equal to (=)', then consider the following statements: 1. If 2x(S)3y and 3x(T)4z, then 9y(P)8z. 2. If x(Q)2y and y(R)z, then x(R)z. Which of the statements given above is/are correct?
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Correct AnswerD
Explanation
Statement 1 actually yields 9y≤8z, not 9y>8z. Statement 2 also does not imply x≤z from x<2y and y≤z. Neither is correct.
Question 5
If 7 ⨁ 9 ⨁ 10 = 8, 9 ⨁ 11 ⨁ 30 = 5, 11 ⨁ 17 ⨁ 21 = 13, what is the value of 23 ⨁ 4 ⨁ 15?
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Correct AnswerA
Explanation
Add the inputs and then sum the digits: 23+4+15=42, giving 6.
Question 6
Consider: I. A+B means A is neither smaller nor equal to B. II. A−B means A is not greater than B. III. A×B means A is not smaller than B. IV. A÷B means A is neither greater nor equal to B. V. A±B means A is neither smaller nor greater than B. Statement: P×Q, P−T, T÷R, R±S. Conclusion-1: Q±T. Conclusion-2: S+Q. Which is correct?
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Correct AnswerB
Explanation
After translating the symbols to inequalities, only the second conclusion follows.
Question 7
Consider the following matrix: 3 8 10 2 ? 1 6 56 90 2 20 0 What is the missing number at ‘?’ in the matrix ?
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Correct AnswerA
Explanation
Each lower entry is the upper entry multiplied by the number immediately below the corresponding pattern: 3×2=6, 8×7=56, 10×9=90, 2×1=2, so ?×4=20 and ?=5.
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