Exercise :: Numbers  General Questions
 Numbers  Important Formulas
 Numbers  General Questions
11.  5358 x 51 = ? 

Answer: Option A Explanation:

12.  The sum of first five prime numbers is: 

Answer: Option D Explanation: Required sum = (2 + 3 + 5 + 7 + 11) = 28. Note: 1 is not a prime number. Definition: A prime number (or a prime) is a natural number that has exactly two distinct natural number divisors: 1 and itself. 
13.  The difference of two numbers is 1365. On dividing the larger number by the smaller, we get 6 as quotient and the 15 as remainder. What is the smaller number ? 

Answer: Option B Explanation: Let the smaller number be x. Then larger number = (x + 1365). x + 1365 = 6x + 15 5x = 1350 x = 270 Smaller number = 270. 
14.  (12)^{3} x 6^{4} ÷ 432 = ? 

Answer: Option A Explanation:

15.  72519 x 9999 = ? 

Answer: Option A Explanation:

16.  If the number 517*324 is completely divisible by 3, then the smallest whole number in the place of * will be: 

Answer: Option C Explanation: Sum of digits = (5 + 1 + 7 + x + 3 + 2 + 4) = (22 + x), which must be divisible by 3. x = 2. 
17.  The smallest 3 digit prime number is: 

Answer: Option A Explanation: The smallest 3digit number is 100, which is divisible by 2. 100 is not a prime number. 101 < 11 and 101 is not divisible by any of the prime numbers 2, 3, 5, 7, 11. 101 is a prime number. Hence 101 is the smallest 3digit prime number. 
18.  Which one of the following numbers is exactly divisible by 11? 

Answer: Option D Explanation: (4 + 5 + 2)  (1 + 6 + 3) = 1, not divisible by 11. (2 + 6 + 4)  (4 + 5 + 2) = 1, not divisible by 11. (4 + 6 + 1)  (2 + 5 + 3) = 1, not divisible by 11. (4 + 6 + 1)  (2 + 5 + 4) = 0, So, 415624 is divisible by 11. 
19.  (?)  19657  33994 = 9999 

Answer: Option A Explanation: 19657 Let x  53651 = 9999 33994 Then, x = 9999 + 53651 = 63650  53651  
20.  The sum of first 45 natural numbers is: 

Answer: Option A Explanation: Let S_{n} =(1 + 2 + 3 + ... + 45). This is an A.P. in which a =1, d =1, n = 45.
= 45 x (20 + 3) = 45 x 20 + 45 x 3 = 900 + 135 = 1035. Shorcut Method:
