Find the odd one out in the given options
A.145
B.197
C.325
D.399

Hint: When we observe the numbers carefully they are all nearer to perfect squares. Either perfect square plus 1 or minus 1. So we will find the odd that won't fit with the rest three. There is a logic that is satisfied by any three options but not the fourth one. And that is our answer.

Complete step-by-step answer:
Given the options are 145, 197, 325 and 399.
Now 399 is the biggest indicator for us as we know that 400 is the perfect square of 20.
So the logic can be a perfect square of a number minus 1.
\[400 - 1 = 399\]
So let’s check!

A.For the first option 145, we can say 144 is the nearest perfect square. But we have to add 1 to it to get the number 145. \[143 + 1 = 144\]
So this is not in our logic.

B.Let’s check option B.
For option two; 197 nearest perfect square is 196 that is square of 14. But here also we have to add 1 to it. That is, \[196 + 1 = 197\]

C.Now we can say the logic is not as we were about to conclude. Let’s check for the third option.
For 325 the nearest square is 324 that is square of 18.

D.Thus, \[324 + 1 = 325\]
Thus option D that is 399 is the odd one out.
So, the correct answer is “Option D”.

Note: Note that, when we solve these types of questions we should not directly jump to conclusions from one or two options only. We should check for all rather the answer can change after two options. So always go for all four options. And check for the logic also. Sometimes it can be related to cubes, prime numbers, odd or even numbers etc.