Question

which number is prime?
4
9
13
10
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Explanation:

Step1: Recall prime number definition

A prime number is a number greater than 1 that has no positive divisors other than 1 and itself.

Step2: Analyze 4

Factorize 4: \(4 = 2\times2\), so it has divisors 2 (other than 1 and 4), not prime.

Step3: Analyze 9

Factorize 9: \(9 = 3\times3\), so it has divisor 3 (other than 1 and 9), not prime.

Step4: Analyze 13

Check divisors of 13. Numbers less than 13: 2,3,4,5,6,7,8,9,10,11,12. None divide 13 evenly. So 13 has only 1 and 13 as divisors, prime.

Step5: Analyze 10

Factorize 10: \(10 = 2\times5\), so it has divisors 2,5 (other than 1 and 10), not prime.

Answer:

13