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Quantitative practice

Number System Questions with Answers

Divisibility, factors, remainders, HCF and LCM, and the unit-digit and last-two-digit shortcuts. This page pools every number system question on the site (163 of them, from 42 exams, weighted towards Management, Banking, Railways) so you can drill the topic on its own instead of meeting four of them inside a full paper.

5% of the pool is graded hard on this site’s own scale and 39% easy, which is gentler than the average topic in this section.

Questions
163
Practice set
25 in 25 min
Difficulty
64/91/8
Negative marking
None
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Number System questions with solutions

6 from the 163-question pool, worked in full.

  1. 1. Find the sum of the first 20 natural numbers.

    • A. 210 ✓
    • B. 200
    • C. 220
    • D. 190

    Solution. Sum of first n natural numbers = n(n+1)/2 = 20 × 21 / 2 = 210.

  2. 2. Find the LCM of 12, 16, and 20.

    • A. 180
    • B. 210
    • C. 240 ✓
    • D. 260

    Solution. 12=2²×3, 16=2⁴, 20=2²×5. LCM takes the highest powers: 2⁴×3×5 = 240.

  3. 3. What is the unit digit of 7⁴⁵?

    • A. 1
    • B. 3
    • C. 9
    • D. 7 ✓

    Solution. The unit digits of powers of 7 cycle through 7, 9, 3, 1. Since 45 leaves a remainder of 1 when divided by 4, the unit digit is 7.

  4. 4. Find the smallest number that, when added to 1,000, makes it exactly divisible by 23.

    • A. 9
    • B. 10
    • C. 11
    • D. 12 ✓

    Solution. 1,000 divided by 23 gives a quotient of 43 with remainder 11 (43×23=989, 1,000−989=11). The smallest number to add = 23−11 = 12.

  5. 5. How many trailing zeroes does 100 factorial have?

    • A. 22
    • B. 24 ✓
    • C. 25
    • D. 26
    • E. 20

    Solution. Trailing zeroes come from factors of 5. There are 20 multiples of 5 up to 100 and 4 multiples of 25, giving 24.

  6. 6. Find the least common multiple of 8, 12 and 16.

    • A. 36
    • B. 44
    • C. 48 ✓
    • D. 52

    Solution. The smallest number divisible by 8, 12, and 16 is 48.

Exams that set Number System

7 categories, led by Management, Banking, Railways.

Also set by JIPMAT, KMAT Karnataka, MICAT, NABARD Grade A, Navy SSR, NMAT, RBI Assistant, RBI Grade B, RPF Constable, RPF Sub-Inspector, RRB ALP, RRB Group D, RRB Junior Engineer, RRB NTPC, RRB Technician, SBI Clerk, SBI PO, SEBI Grade A, SIDBI Grade A & B, SNAP, SSC CGL, SSC CHSL, SSC CPO, SSC GD Constable, SSC Selection Post, TANCET MBA, UKPSC PCS, UPPSC PCS, UPSC CSE, XAT. Browse all exams.

Number System: frequently asked questions

How many number system questions are there?

163, from the 42 exams here whose syllabus sets the topic. 39% are graded easy and 5% hard, which makes number system one of the more tractable topics in this section, against a 17% average.

Which exams ask number system questions?

42 of the exams on this site, weighted towards Management (13), Banking (10), Railways (7). Every question in this pool comes from one of their own mock tests, so the list below is the honest answer to whether the topic is worth your time.

Is number system hard?

5% of these 163 questions are graded hard and 39% easy, making it one of the more tractable topics in this section, against a 17% average.

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