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UPSC Prelims 2025 CSAT, question 38

Topic: Arithmetic

Q38

If P=+,Q=−,R=×,S=÷P=+,Q=-,R= \times ,S= \div, then insert the proper notations between the successive numbers in the equation 60_15_3_20_4 = 20 :

  1. (a) SPRQ
  2. (b) QRPSCorrect answer
  3. (c) QRSP
  4. (d) SPQR

Solution.

Answer: (b) QRPS

  1. Testing option (b) QRPS (Q=−,R=×,P=+,S=÷Q = -, R = \times, P = +, S = \div) in 60_15_3_20_460 \_ 15 \_ 3 \_ 20 \_ 4 gives 60−15×3+20÷460 - 15 \times 3 + 20 \div 4.
  2. By standard order of operations (BODMAS), 60−(15×3)+(20÷4)=60−45+5=2060 - (15 \times 3) + (20 \div 4) = 60 - 45 + 5 = 20.