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RBI Assistant Number System & Simplification Questions
Practise number system & simplification (quantitative aptitude) for the RBI Assistant Examination: 10 multiple-choice questions, each with the correct answer and a worked explanation. Click an option to check it, or “New questions” for another set.
Number System & Simplification practice
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Q1.Find the HCF of 20 and 20.
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Answer: D — 20
HCF(20, 20) = 20. Check: HCF × LCM = 20 × 20 = 400 = product of the numbers.
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Q2.Find the LCM of 40 and 72.
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Answer: C — 360
LCM(40, 72) = 360. Check: HCF × LCM = 8 × 360 = 2880 = product of the numbers.
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Q3.Find the HCF of 77 and 99.
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Answer: A — 11
HCF(77, 99) = 11. Check: HCF × LCM = 11 × 693 = 7623 = product of the numbers.
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Q4.Simplify: 87 + 3 × 3 − 50
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Answer: B — 46
BODMAS: multiply first — 3 × 3 = 9; then 87 + 9 − 50 = 46.
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Q5.Find the LCM of 108 and 60.
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Answer: B — 540
LCM(108, 60) = 540. Check: HCF × LCM = 12 × 540 = 6480 = product of the numbers.
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Q6.Simplify: 58 + 6 × 8 − 44
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Answer: D — 62
BODMAS: multiply first — 6 × 8 = 48; then 58 + 48 − 44 = 62.
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Q7.Find the LCM of 56 and 72.
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Answer: A — 504
LCM(56, 72) = 504. Check: HCF × LCM = 8 × 504 = 4032 = product of the numbers.
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Q8.What is √1,764?
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Answer: D — 42
42 × 42 = 1764, so √1764 = 42.
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Q9.Simplify: 48 + 12 × 2 − 29
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Answer: D — 43
BODMAS: multiply first — 12 × 2 = 24; then 48 + 24 − 29 = 43.
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Q10.Find the next number in the series: 16, 25, 36, 49, 64, ?
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Answer: B — 81
Squares of consecutive numbers: 4², 5², … → 9² = 81.
How to approach number system & simplification questions
Learn squares to 30 and cubes to 15, apply BODMAS strictly, and use HCF × LCM = product of two numbers. For series, check the differences first, then the ratios.
About RBI Assistant
RBI Assistant Examination — conducted by Reserve Bank of India (RBI). Recruits Assistants for RBI offices through prelims, mains and a language proficiency test.
Original practice questions written for this site in the style and difficulty of each exam’s syllabus. They are not past papers and the site is not affiliated with any exam body. Exam patterns, marking schemes and syllabi change — always check the latest official notification.
RBI Assistant practice topics
| Topic | Section | Question source |
|---|---|---|
| Number System & Simplification | Quantitative aptitude | Calculated (new numbers every set) |
| Logical Reasoning | Reasoning | Calculated (new numbers every set) |
| English Grammar | English | Question bank |
| Economy & Banking Awareness | General awareness | Question bank |
| Computer Awareness | Computer knowledge | Question bank |