Correct Answer - Option 3 : 257

Given: 429, 336, 257, 259

All the numbers except option (3), the given number is exactly divisible by any number.

Here we see only **257** is the prime number.

Option 1: 429 → It is divisible by 3.

Option 2: 336 → It is divisible by 3.

Option 4: 259 → It is divisible by 7.

**Hence, the correct answer is 257.**

- The priority will always be the prime number in the exams.
- There are some standard rules which need to be followed while selecting the priority.
- priority lists to be followed in exams according to their preferences are:

- Prime number.
- Square.
- Cube.
- Multiplication and divisions
- Addition and subtraction.

- A prime number can be divided, without a remainder, only by itself and by 1.
- Some facts about the Prime numbers:

- The only even prime number is 2. All other even numbers can be divided by 2.
- If the sum of a number's digits is a multiple of 3, that number can be divided by 3.
- No prime number greater than 5 ends in a 5. Any number greater than 5 that ends in a 5 can be divided by 5.
- Zero and 1 are not considered prime numbers.
- Except for 0 and 1, a number is either a prime number or a composite number. A composite number is defined as any number, greater than 1, that is not prime.