You could say that the odd one out is D)30, because it's the only one that isn't even in the question. Actually, though, I think that the intent of the question is that the one one out is A)28, the only number in the question that's not divisible by 3.

...Divide them, or just the last digit, by 2. If the rest is 0, then it's even. if the rest is 1 it's odd.

(Much more easier, even numbers end with 0-2-4-6-8, odd numbers with 1-3-5-7-9)

here the even number is A, 28

All of them except 28 is divisible by 3.

24/3 = 8

21/3 = 7

12/3 = 4

But 28/3 does not equate to a whole number. The answer is A

When you look at all of the choices, except the number 28, they all have a factor of "3" in common. So choice 'A' is the odd one out.

...The answer is A. 28 because 28 is the only integer which cannot be divided by 3 while others can be divided by 3.

Hope this will help.

The answer is A . 28 . All the others are divisiable by 3 i.e 9/3=3, 21/3=7, 24/3=8 and 12/3=4

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