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LCM and HCF Practice Test 4

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Question : 17 of 40

Marks: +1, -0

H.C.F. of 420, 315 and 462 is

24
28
27
21

Solution:

Concept:

H.C.F. is the product of the common prime factors, each taken with its lowest power.

Explanation:

Prime factorise each number:

420 = 2^2 \times 3 \times 5 \times 7

315 = 3^2 \times 5 \times 7

462 = 2 \times 3 \times 7 \times 11

Common prime factors are

3

and

7

.

Lowest powers:

3^1

and

7^1

.

H.C.F.

= 3 \times 7 = 21

.

Answer:

21

, which is option D.

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