HCF ChallengeOnline version Find the greatest common factor of pairs. by Arnab Biswas 1 Find the HCF of 24 and 60. a 12 b 8 c 24 d 6 2 Find the HCF of 81 and 27. a 27 b 3 c 9 d 81 3 Find the HCF of 14 and 21. a 2 b 3 c 7 d 1 4 Find the HCF of 100 and 25. a 5 b 10 c 20 d 25 5 Find the HCF of 36 and 48. a 18 b 24 c 6 d 12 6 Find the HCF of 7 and 13. a 7 b 13 c 1 d 2 7 Find the HCF of 48 and 180. a 18 b 60 c 12 d 6 8 Find the HCF of 270 and 360. a 30 b 90 c 45 d 60 9 Find the HCF of 51 and 85. a 3 b 85 c 5 d 17 10 Find the HCF of 12 and 15. a 5 b 1 c 3 d 2