Q13 of 18 Page 88

Using Euclid’s division algorithm, find whether the HCF of 847 and 2160 is co-prime or not?

According to Euclid’s Division Lemma, if a and b are any two positive integers then there exist two unique whole numbers q and r such that

a = b q + r,


where 0 ≤ r < b


Here, a is called the dividend,


b is called the divisor,


q is called the quotient and


r is called the remainder.


So, apply the lemma on 2160 and 847.


We get,


2160 = (847 × 2) + 466


Since the remainder is not zero.


Apply the lemma again on 847 and 466.


We get,


847 = (466 × 1) + 381


Since the remainder is not zero.


Apply the lemma again on 466 and 381.


We get,


466 = (381 × 1) + 85


Since the remainder is not zero.


Apply the lemma again on 381 and 85.


We get,


381 = (85 × 4) + 41


Since the remainder is not zero.


Apply the lemma again on 85 and 41.


We get,


85 = (41 × 2) + 3


Since the remainder is not zero.


Apply the lemma again on 41 and 3.


We get,


41 = (3 × 13) + 2


Since the remainder is not zero.


Apply the lemma again on 3 and 2.


We get,


3 = (2 × 1) + 1


Since the remainder is not zero.


Apply the lemma again on 2 and 1


We get,


2 = (1 × 2) + 0


We have finally got remainder as 0.


HCF (847, 2160) = 1


If the HCF of 847 and 2160 is 1, then the numbers are co-primes.


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