Directions: Find the odd man out: 253, 136, 352, 460, 324, 631, 244

### Concept & Sum of Digits When dealing with a set of seemingly random large numbers, a common property that binds them is the sum of their individual digits being a constant value. ### Step-by-Step Solution 1. Calculate the sum of the digits for each number: - $253 \rightarrow 2 + 5 + 3 = 10$ - $136 \rightarrow 1 + 3 + 6 = 10$ - $352 \rightarrow 3 + 5 + 2 = 10$ - $460 \rightarrow 4 + 6 + 0 = 10$ - $631 \rightarrow 6 + 3 + 1 = 10$ - $244 \rightarrow 2 + 4 + 4 = 10$ 2. Now, evaluate $324$: - $324 \rightarrow 3 + 2 + 4 = 9$ 3. All numbers in the series have a digit sum of $10$, except for $324$, which has a digit sum of $9$. 4. Hence, $324$ is the odd man out. ### Exam Strategy & Shortcut For $3$-digit grouping questions, mentally scan the digit sums ($10, 10, 10...$) as your first or second diagnostic step. It takes seconds and often yields the answer immediately. ### Common Pitfall Trying to find an alternating difference or multiplying the digits, which leads nowhere and consumes valuable time that should be spent recognizing the simple addition property. ### Final Answer Therefore, the correct answer is **324**.