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Question

Find the odd one out in the set: {19, 37, 21, 17, 23, 29, 31, 11}

The correct answer is
21

Odd One Out: Identifying the Composite Number

The question requires identifying the number that does not share a common property with the rest of the numbers in the set {19, 37, 21, 17, 23, 29, 31, 11}. We need to analyze the properties of each number.

Number Properties Analysis

  • 19: Prime number (only divisible by 1 and 19).
  • 37: Prime number (only divisible by 1 and 37).
  • 21: Composite number (divisible by 1, 3, 7, and 21).
  • 17: Prime number (only divisible by 1 and 17).
  • 23: Prime number (only divisible by 1 and 23).
  • 29: Prime number (only divisible by 1 and 29).
  • 31: Prime number (only divisible by 1 and 31).
  • 11: Prime number (only divisible by 1 and 11).

Conclusion

All the numbers in the given set are prime numbers, except for the number 21, which is a composite number. Therefore, 21 is the odd one out.

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Important Questions from Number System

  1. Consider the following statements :

    1. (25)! + 1 is divisible by 26

    2. (6)! + 1 is divisible by 7

    Which of the above statements is/are correct ?

  2. If the sum S is divided by 8, what is the remainder ?  

  3. If the sum S is divided by 60, what is the remainder ?

  4. Find the sum of squares of the greatest value and the smallest value of K in the number so that the number 45082K is divisible by 3.

  5. How many composite numbers are there from 53 to 97 ?

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