1. Which pairs are co-prime?
a. 16, 18 b. 5 ,14 c. 6, 15. d. 45 ,48
2. .HCF of ( 52 ,320 ) is equal to:
a.8 b.4. c. 5 d. 1
3. Given that LCM (91 ,26 ) = 182. Then HCF (91, 26 ) is
3. b. 26. C. 18 C. 9
4. Using prime factorisation, find the HCF and LCM of:
(i) 8,9,25
(ii) 12, 15, 21
(iii) 17,23, 29
(iv) 24, 36, 40
(v) 30, 72, 432
(vi) 21, 28, 36
5. Find HCF and LCM of 404 and 96 and verify that HCF x LCM = product of two given numbers.
6.Two positive integers a and b can be written as a = x³ y² and b = x y³ ,where x and y are prime numbers. Find HCF(a, b) and LCM(a, b).
7. The HCF of two numbers is 23 and their LCM is 1449. If one of the numbers is 161, find the other.
8. The HCF of two numbers is 145 and their LCM is 2175. If one of the
numbers is 725, find the other.
9. The HCF of two numbers a and b is 5 and their LCM is 200. Find the
product ab.
10 . The LCM of two numbers is 9 times their HCF. The sum of LCM and HCF is 500. Find their HCF..
11. The HCF of two numbers is 18 and their product is 12960. Find their LCM.
12. Can two numbers have 15 as their HCF and 175 as their LCM? Give
13. Prove that 2½ is an irrational
number.
14. Prove that 7½ -5 is an irrational number.
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