HCF and LCM Worksheet-1

HCF and LCM Worksheet-1

Mark against the correct answer:

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

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

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

3. 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

4.  when expressed in simplest form is :

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

5. Reduce to its lowest terms,

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

6. 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

7. 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

8. 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

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

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

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

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

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

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

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

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

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

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

14. 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

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

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

16. The L.C.M. of 22, 54, 108, 135 and 198 is :

(a) 330               (b) 1980             (c) 5940             (d) 11880

17. The L.C.M. of 148 and 185 is :

(a) 680               (b) 740               (c) 2960             (d) 3700

18. The H.C.F. of and is :

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

19. The H.C.F. of and is :

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

20. The L.C.M. of is:

(a)                 (b)                 (c)                 (d) None of these

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); (16)-(c); (17)-(b); (18)-(b); (19)-(c); (20)-(c)