Which ofthe following statements are true?
(a) If anumber is divisible by 3, it must be divisible by 9.
(b) If anumber is divisible by 9, it must be divisible by 3.
(c) Anumber is divisible by 18, if it is divisible by both 3 and 6.
(d) If anumber is divisible by 9 and 10 both, then it must be divisible by90.
(e) If twonumbers are co-primes, at least one of them must be prime.
(f) Allnumbers which are divisible by 4 must also be divisible by 8.
(g) Allnumbers which are divisible by 8 must also be divisible by 4.
(h) If a number exactly divides two numbers separately, it mustexactly divide their sum.
(i) If a number exactly divides the sum of two numbers, it mustexactly divide the two numbers separately.
(a) False
6 is divisible by 3, but not by 9.
(b) True,as 9 = 3 × 3
Therefore, if a number is divisible by 9, then it will also bedivisible by
3.
(c) False
30 is divisible by 3 and 6 both, but it is not divisible by 18.
(d) True,as 9 × 10 = 90
Therefore, if a number is divisible by 9 and 10 both, then it willalso be divisible by 90.
(e) False
15 and 32 are co-primes and also composite.
(f) False
12 is divisible by 4, but not by 8.
(g) True,as 8 = 2 × 4
Therefore, if a number is divisible by 8, then it will also bedivisible by 2 and 4.
(h) True
2 divides 4 and 8 as well as 12. (4 + 8 = 12)
(i) False
2 divides 12, but does not divide 7 and 5.