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Home › Grade8 › OLYMPIAD › Math Olympiad-Grade-8 › H.C.F. & L.C.M. of Numbers › H.C.F. & L.C.M. of Numbers Worksheet-1

H.C.F. & L.C.M. of Numbers Worksheet-1

H.C.F. & L.C.M. of Numbers Worksheet-1

 

  1. 252 can be expressed as a product of primes as :

(a) 2 × 2 × 3 × 3 × 7                    (b) 2 × 2 × 2 × 3 × 7

(c) 3 × 3 × 3 × 3 × 7                    (d) 2 × 3 × 3 × 3 × 7

 

  1. Which of the following has most number of divisors?

(a) 99                  (b) 101                (c) 176                (d) 182

 

  1. A number n is said to be perfect if the sum of all its divisors (excluding n itself) is equal to n. An example of perfect number is :

(a) 6                    (b) 9                    (c) 15                   (d) 21

 

  1.  when expressed in simplest form is :

(a)                  (b)                  (c)                 (d)

 

  1. Reduce to its lowest terms,

(a)                   (b)                  (c)                  (d)

 

  1. The H.C.F. of 22 × 33 × 55, 23 × 32 × 52 × 7 and 24 × 34 × 5 × 72 × 11 is:

(a) 22 × 32 × 5                               (b) 22 × 32 × 5 × 7 × 11

(c) 24 × 34 × 55                              (d) 24 × 34 × 55 × 7 × 11

 

  1. The H.C.F of 24 × 32 × 53 × 7, 23 × 33 × 52 × 72 and 3 × 5 × 7 × 11 is :

(a) 105                (b) 1155              (c) 2310             (d) 27720

 

  1. H.C.F. of 4 × 27 × 3125, 8 × 9 × 25 × 7 & 16 × 81 × 5 × 11 × 49 is :

(a) 180               (b) 360               (c) 540               (d) 1260

 

  1. Find the highest common factor of 36 and 84.

(a) 4                    (b) 6                    (c) 12                  (d) 18

 

  1. The H.C.F. of 204, 1190 and 1445 is :

(a) 17                  (b) 18                  (c) 19                  (d) 21

 

  1. Which of the following is a pair of co-primes?

(a) (16, 62)        (b) (18, 25)        (c) (21, 35)        (d) (23, 92)

 

  1. The H.C.F. of 2923 and 3239 is :

(a) 37                  (b) 47                  (c) 73                  (d) 79

 

  1. The H.C.F. of 3556 and 3444 is:

(a) 23                  (b) 25                  (c) 26                  (d) 28

 

  1. The L.C.M. of 23 × 32 × 5 × 11, 24 × 34 × 52 × 7 and 25 × 33 × 53 × 72 × 11 is:

(a) 23 × 32 × 5                               (b) 25 × 34 × 53 

(c) 23 × 32 × 5 × 7 × 11                (d) 25 × 34 ×  53 × 72 × 11

 

  1. Find the lowest common multiple of 24, 36 and 40.

(a) 120                (b) 240               (c) 360               (d) 480

 

Answer Key:

(1)-a; (2)-c; (3)-a; (4)-b; (5)-c; (6)-a; (7)-a; (8)-a; (9)-c; (10)-a; (11)-b; (12)-d; (13)-d; (14)-d; (15)-c