scuva wrote:
I do not get the co-prime importance here. Could someone explain how we choose 3 pairs?
Hey, I think that I understand why. It took me some time to understand.
Look on this pair:
24 | 192
24 + 192 = 216
But if you check, the question asks about HCF (HIGHEST common).
It you look on 24 and 192,
24:24=1 and 192:24=8 so the hcf here is not 12 but 24.
Now check:
12 | 204 (HCF = 12) - Correct
24 | 192 (HCF = 24)
36 | 180 (HCF = 36)
48 | 168 (HCF = 24)
60 | 156 (HCF = 12) - Correct
72 | 144 (HCF = 24)
84 | 132 (HCF = 12) - Correct
96 | 120 (HCF = 24) - Correct
108 | 108 (HCF = 108)
Divide each pair by 12, and you will see why it should be co-prime.
60 | 156 ===> 5 | 13
But
24 | 192 ===> 2 | 16 ===> Here you also have 2 so the HCF is 12x2=24.