3,7,10,15,19,21,35,111 which of these are prime numbers

To determine which of the numbers are prime, we need to check if each number has exactly two distinct positive divisors: 1 and itself.

Let's examine each number:

1. **3**: Prime (only divisible by 1 and 3)
2. **7**: Prime (only divisible by 1 and 7)
3. **10**: Not prime (divisible by 1, 2, 5, and 10)
4. **15**: Not prime (divisible by 1, 3, 5, and 15)
5. **19**: Prime (only divisible by 1 and 19)
6. **21**: Not prime (divisible by 1, 3, 7, and 21)
7. **35**: Not prime (divisible by 1, 5, 7, and 35)
8. **111**: Not prime (divisible by 1, 3, 37, and 111)

**Prime numbers in the list are: 3, 7, and 19.**

Would you like further explanation on checking prime numbers or have any other questions?

### Related Questions:
1. How do you identify a prime number efficiently?
2. What are composite numbers, and how are they different from prime numbers?
3. Can prime numbers be negative, and why or why not?
4. Are 0 and 1 considered prime or composite?
5. Why are prime numbers important in cryptography and security?

### Tip:
When checking if a number is prime, you only need to test divisibility up to its square root.

Learn how to determine which numbers are prime in the list 3, 7, 10, 15, 19, 21, 35, 111. This step-by-step solution explores number theory basics and prime number identification for Grades 5-7.

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