divisibility rules for 9 and 3

Question

is 3 and 9 divisible by 450 537 666

Answer 1

the rules are:

for divisibility by 9- if the sum of the digits that form the number is divisible by 9 then the original number is divisible by 9

for divisibility by 3- if the sum of the digits that form the number is divisible by 3 then the original number is divisible by 3

if a number is divisible by 9 then it is automatically divisible by 3

but, if a number is divisible by 3 it is not necessarily divisible by 9

Answer 2

You have the wording backward. 450, 537 and 666 are divisible by 3, but 537 is not divisible by 9.