21. If we divide the sum of 45 and 90 by their difference, the answer is
(A) Neither prime nor composite
(B) The least prime number
(C) The least odd Prime number
(D) The least composite number
Answer:
(C) The least odd Prime number
Explanation:
The sum is 45 + 90 = 135. The difference is 90 – 45 = 45. The division is 135 ÷ 45 = 3. The number 3 is the least odd prime number.
22. I am a prime number. If you subtract 1 from me, I will become divisible by 9. Who am I?
(A) 29
(B) 19
(C) 17
(D) 11
Answer:
(B) 19
Explanation:
Testing the options: 19 is a prime number, and 19 – 1 = 18, which is divisible by 9.
23. HCF of 90, 96, and 10 is
(A) 2
(B) 6
(C) 10
(D) 1
Answer:
(A) 2
Explanation:
The factors of 10 are 1, 2, 5, 10. Both 90 and 96 are divisible by 2. They are not both divisible by 5 or 10. Therefore, the Highest Common Factor (HCF) is 2.
24. Compare 119 ☐ 52
(A) =
(B) >
(C) <
(D) None of these
Answer:
(B) >
Explanation:
To compare the fractions, convert them to decimals: 119 is approximately 0.818, and 52 is 0.4. Since 0.818 is greater than 0.4, 119 > 52.
25. The largest prime number between 1 and 100 is
(A) 89
(B) 97
(C) 99
(D) 93
Answer:
(B) 97
Explanation:
A prime number is only divisible by 1 and itself. 97 is the largest number less than 100 that fits this description.
