Question

Of the given pairs of numbers, the pair(s) of co-prime numbers is/are:
(i) 231, 396
(ii)847, 2160

• A. Only (i)
• B. Only (ii)
• C. Both (i) and (ii)
• D. Neither (i) nor (ii)

Answer 1

The correct option is B Only (ii)

Let us find the H.C.F of each pair of number
(i)$396=231\times 1+165$
$231=165\times 1+66$
$165=66\times 2+33$
$66=33\times 2+0$
Therefore the HCF=33. Hence the numbers are not co-prime
(ii)$2610=847\times 2+466$
$847=466\times 1+381$
$466=381\times 1+85$
$381=85\times 4+41$
$85=41\times 2+3$
$41=3\times 13+2$
$3=2\times 1+1$
$2=1\times 2+0$
Therefore the H.C.F=1. Hence the numbers are co-prime.