378 is divisible by both 3 and 9 with no remainders
Yes.
Yes because the digital sum of 378 add up to 9 and 378/9 = 42
Yes.
Multiples of 9 and 6 are also divisible by three, the reverse is not true. 15 is divisible by 3, but not 6 or 9. 27 is divisible by 3 and 9, but not 6. 12 is divisible by 3 and 6, but not 9. 54 is divisible by 3, 6 and 9.
3 yes, 9, no.
Yes.
Yes because the digital sum of 378 add up to 9 and 378/9 = 42
yes its 126
Yes.
None of them are divisible by 4.
1, 2, 3, 6, 7, 9, 14, 18, 21, 27, 42, 54, 63, 126, 189, and 378.
Because its final digital sum equals 9
All numbers divisible by 3 are NOT divisible by 9. As an example, 6, which is divisible by 3, is not divisible by 9. However, all numbers divisible by 9 are also divisible by 3 because 9 is divisible by 3.
If you mean, "What are the factors of 378?", they are: 1, 2, 3, 6, 7, 9, 14, 18, 21, 27, 42, 54, 63, 126, 189, and 378. If you mean, "What are the composite factors of 378?", they are: 6, 9, 14, 18, 21, 27, 42, 54, 63, 126, 189, and 378. If you mean, "Which of 3, 7, and 8 are composite numbers?", the only one is 8.
No.
No.
No, it is not.