3 & 4
If they are multiples of 9, the digits add up to a multiple of 9.
12 over 13. Common factor of 6. (Digits add to a number divisible by 3 and they are even). 12 over 13.
Yes, because the digits of 261 add up to a multiple of 3.
9
Add up the digits of 291. If they total a multiple of 9, 9 is a factor.
12
66
Yes. If 492 is even, it has 2 as a factor. If its digits add up to a multiple of 3, it has 3 as a factor. If it has 2 and 3 as a factor, it has 6 as a factor.
The greatest common factor of 123 and 234 is 3.123: the digits (1, 2, 3) add up to 6.234: the digits (2, 3, 4) add up to 9.So both 6 and 9 are divisible by three.More formally:The prime factors of 123 are 3 and 41, while the prime factors of 234 are 2, 3, 3, and 13. The intersection of [3, 41] and [2, 3, 3, 13] is [3], therefore the Greatest Common Factor (GCF) of 123 and 234 is 3.
A number is divisible by 9 if all the digits add up to 9 or are a factor of. IF the digits add up to 9 (or a factor of 9), they will automatically be a factor of 3.Yes. Test a couple numbers divisible by 9--27, 81--and they are all divisible by 3.
127
If you add all the digits up, and the total equals a number that 3 can go in, then it's a factor of 3.