Playing With Numbers

16. The number of common prime factors of 75, 60 and 105 is

• (A) 2
• (B) 3
• (C) 4
• (D) 5

15. Which of the following numbers is divisible by 11?

• (A) 1011011
• (B) 1111111
• (C) 22222222
• (D) 3333333

14. What is the value of x if 92x389 is divisible by 11?

• (A) 9 
• (B) 7 
• (C) 6
• (D) 8

13. What is the value of y if 8y9484 is divisible by 11?

• (A) 9 
• (B) 7 
• (C) 6
• (D) 8

12. LCM of 10, 15 and 20 is

• (A) 30
• (B) 60
• (C) 90
• (D) 180

11. Every factor of a number x is

• (A) < x
• (B) > x
• (C) ≤ x
• (D) = x

10. Every multiple of a number x is

• (A) ≤ x
• (B) > x
• (C) ≥ x
• (D) = x

9. If a number is divisible both by 2 and 3, then it must be divisible by  

• (A) 4
• (B) 6
• (C) 9
• (D) None of these

8. If the digit in one’s place of a number is any of the digits 0, 2, 4, 6 or 8, the number is always divisible by

• (A) 4
• (B) 2
• (C) 3
• (D) 5

7. The sum of all the multiples of 9 from 89 to 100 is

• (A) 188       
• (B) 189       
• (C) 190       
• (D) 191

6. If the HCF of two numbers is one of the numbers, then their LCM is

• (A) 1 
• (B) HCF      
• (C) The other number    
• (D) 2

5. If x ≠ y, which of the following is true?

• (A) LCM (x, y) = HCF (x, y)      
• (B) LCM (x, y) ≥ HCF (x, y)      
• (C) LCM (x, y) ≤ HCF (x, y)      
• (D) None of these

4 LCM of two numbers is 180. Then which of the following is not the HCF of the numbers?

• (A) 45
• (B) 60
• (C) 75
• (D) 90

3. A whole number is added to 25 and the same number is subtracted from 25. The sum of the resulting numbers is

• (A) 0
• (B) 25
• (C) 50
• (D) 75

2. Which of the following is not true?

• (A) (7 + 8) + 9 = 7 + (8 + 9)
• (B) (7 × 8) × 9 = 7 × (8 × 9)
• (C) 7 + 8 × 9 = (7 + 8) × (7 + 9)
• (D) 7 × (8 + 9) = (7 × 8) + (7 × 9)

1. By using dot (.) patterns, which of the following numbers can be arranged in all the three ways namely a line, a triangle and a rectangle?

• (A) 9
• (B) 10
• (C) 11
• (D) 12