Q 21 :    

The last number that is divisible by all the numbers from 1 to 8 (both inclusive) is

  • 840

     

  • 2520

     

  • 8

     

  • 420

     

(1)

Explanation: LCM of 1, 2, 3, 4, 5, 6, 7, 8 = 23 × 3 × 5 × 7 = 840

 



Q 22 :    

The product of two consecutive natural numbers is always

  • Prime number

     

  • Even number

     

  • Odd number

     

  • Even or Odd

     

(2)

 



Q 23 :    

If the HCF of 408 and 1032 is expressible in the form 1032 x 2 + 408 x p, then the value of p is

  • 5

     

  • – 5

     

  • 4

     

  • – 4

     

(2)

Explanation HCF of 408 and 1032 is 24,

 1032 x 2 + 408 x (p) = – 24

408p = 24 – 2064

408p = 0150 2040

p = - 2040408 = - 5



Q 24 :    

The number in the form of 4p + 3, where p is a whole number, will always be

  • Even

     

  • Odd

     

  • Even or Odd

     

  • Multiple of 3

     

(2)

Explanation: 

p = 1                    p = 24(p) + 3 = 7       4(p) + 3 = 11

 



Q 25 :    

If p2 = 3250, then p is a/an

  • Whole number

     

  • Integer

     

  • Rational Number

     

  • Irrational number

     

(3)

We have, p2 = 3250 = 1625

 p = ± 45 (Rational Number)

 



Q 26 :    

The LCM of smallest 2-digit number and smallest composite number is

  • 12

     

  • 4

     

  • 20

     

  • 40

     

(3)

Smallest 2 digit number = 10 = 2 x 5

Smallest composite number = 4 = 22

 LCM (10, 4)22 x 5 = 20

 



Q 27 :    

The ratio of HCF to LCM of the least composite number and the least prime number is:

  • 1 : 2

     

  • 2 : 1

     

  • 1 : 1

     

  • 1 : 3

     

(1)

Least Composite number is = 4 = 22

Least Prime number is 2 = 21

HCF (4, 2) is 21 = 2

LCM (4, 2) is 22 = 4

 HCFLCM = 24 = 12 i.e., 1 : 2



Q 28 :    

To enhance the reading skills of grade X students, the school nominates you and two of your friends to set up a class library. There are two Sections - Section A and Section B of grade X. There are 32 students in Section A and 36 students in Section B.

Q: If the product of two positive integers is equal to the product of their HCF and LCM is true then, the HCF (32, 36) is

  • 2

     

  • 4

     

  • 6

     

  • 8

     

(2)

Explanation: HCF x LCM = 32 x 36

HCF = 32 × 36LCM = 1152288 = 4

HCF = 4