Which of the following statements are true? (a) If a number is divisible by 3, it must be divisible by 9.

NCERT Math Class 6th Question – 1 Exercise 3.5

Which of the following statements are true?

(a) If a number is divisible by 3, it must be divisible by 9.
(b) If a number is divisible by 9, it must be divisible by 3.
(c) A number is divisible by 18, if it is divisible by both 3 and 6.
(d) If a number is divisible by 9 and 10 both, then it must be divisible by 90.
(e) If two numbers are co-primes, at least one of them must be prime.
(f) All numbers which are divisible by 4 must also be divisible by 8.
(g) All numbers which are divisible by 8 must also be divisible by 4.
(h) If a number exactly divides two numbers separately,- it must exactly divide their sum.
(i) If a number exactly divides the sum of two numbers, it must exactly divide the two numbers separately.

Solution: 

(a) False
(b) True
(c) False
(d) True
(e) False
(f) False
(g) True
(h) True
(i) False