Find the LCM of 84 and 140.

The correct answer is A: 420. This question asks us to find the least common multiple (LCM) of two numbers using prime factorization. Step 1: Find prime factorization of 84 Break 84 into its prime factors by dividing by smallest primes. $$84 = 2^2 \times 3 \times 7$$ Step 2: Find prime factorization of 140 Break 140 into its pri

How many factors does the number 36 have?

The correct answer is B: 9. 36 = 2² × 3². Number of factors = (2+1)(2+1) = 3 × 3 = 9. The factors are: 1, 2, 3, 4, 6, 9, 12, 18, 36.

A shopkeeper marks goods at 60% above cost price and gives a discount of 25%. What is his profit percentage?

The correct answer is C: 20%. Let CP = 100. MP = 160. SP = 160 × 0.75 = 120. Profit% = 20%

The LCM of two numbers is 48 and their HCF is 4. If one number is 16, find the other number.

The correct answer is A: 12. Use the formula: HCF × LCM = Product of two numbers. So 4 × 48 = 16 × other number. Therefore 192 = 16 × other number, which gives other number = 192/16 = 12.

What is the sum of all even numbers between 1 and 101?

The correct answer is B: 2550. Even numbers: 2, 4, 6, ..., 100. This is AP with a=2, l=100, d=2. n = 50 terms. Sum = (n/2)(a+l) = (50/2)(2+100) = 25×102 = 2550.

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Quantitative aptitude questions for competitive exams

82 Q 7 Topics Take Mock Test

Difficulty: All Easy Medium Hard 81–82 of 82

Topics in Quantitative Aptitude

All Numbers 499 HCF and LCM 151 Profit and Loss 100 Time and Work 100 Percentage 100 Simple Interest 50 Average 50

Q.81 Hard Numbers

What is the sum of all divisors of 28?

A 56

B 64

C 72

D 84

Correct Answer: A. 56

EXPLANATION

Divisors of 28: 1, 2, 4, 7, 14, 28.

Sum = 1+2+4+7+14+28 = 56. (Note: 28 is a perfect number where sum of proper divisors = 28)

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Q.82 Hard Numbers

A number has exactly 3 factors. Which of the following must be true?

A It is a perfect square

B It is the square of a prime number

C It is divisible by 3

D It is an even number

Correct Answer: B. It is the square of a prime number

EXPLANATION

A number has exactly 3 factors only when it is the square of a prime.

For p² where p is prime, factors are: 1, p, p².

Example: 4 has factors 1,2,4 (3 factors). 9 has factors 1,3,9 (3 factors).

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Quantitative Aptitude Numbers

Quantitative Aptitude
Numbers