Direction: Read the question and answer accordingly.
1. If we write down all the natural numbers from 259 to 492 side by side get a very large natural number 259260261....491492.
How many 8(s) will be used to write this large natural number?
Answer: Option D
Explanation: Total 8(s)From 259 to 458 = 40
Total 8(s) From 459 to 492 = 13
Totl 8(s) = 40 + 13 = 53
2. The LCM of two numbers is 280 and their ratio is 7:8. The two numbers are
A. 70, 80
B. 35, 40
C. 42, 48
D. 28,32
Answer: Option B
Explanation: Let the number be 7x and 8x
HCF = x
Hence, HCF × LCM = 7x × 8x
⇒ 280x = 56x × x
⇒ x = 5
Thus numbers are 35 and 40.
3. If each of the three nonzero numbers a, b and c is divisible by 3, then abc must be divisible by which one of the following the numbers?
Answer: Option B
Explanation: Since each one of the three numbers a, b, and c is divisible by 3, the numbers can be represented as 3p,3q and 3r, respectively, where p,q and r are integers.
The product of the three numbers is 3p × 3q ×3r = 27(pqr).
Since p, q and r are integers, pqr is an integer and therefore abc is divisible by 27.
4. A girl wrote all the numbers from 100 to 200. Then she started counting the number of one's that has been used while writing all these numbers. What is the number that she got?
A. 111
B. 119
C. 120
D. 121
Answer: Option C
Explanation: From 100 to 200 there are 101 numbers.
There are 100, 1's in the hundreds place.
10, 1's in tens place and10, 1's in-unit place.
Thus, the answer is 100 + 10 + 10 = 120.
5. Which of the following has most number of divisors?
A. 90
B. 101
C. 176
D. 182
Answer: Option C
Explanation: Divisors of 99 = 1, 3, 9, 11, 33, 99
Divisors of 101 = 1, 101
Divisors of 176 = 1, 2, 4, 8, 11, 22, 44, 88, 176
Divisors of 182 = 1, 2, 7, 13, 14, 26, 91, 182