Prime numbers

Front

What is a prime number?

Back

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

Front

List the first five prime numbers.

Back

2, 3, 5, 7, 11.

Front

Is 1 a prime number? Why or why not?

Back

No, 1 is not a prime number because it does not meet the definition of having exactly two distinct positive divisors.

Front

What are the only two factors of a prime number?

Back

1 and the prime number itself.

Front

How can you determine if a number is prime?

Back

To determine if a number is prime, check if it has any divisors other than 1 and itself by testing divisibility with prime numbers up to its square root.

Front

What is the largest prime number less than 20?

Back

19.

Front

Are all even numbers prime?

Back

No, the only even prime number is 2; all other even numbers are divisible by 2 and thus have at least three factors.

Front

What is the Sieve of Eratosthenes?

Back

The Sieve of Eratosthenes is an ancient algorithm used to find all prime numbers up to a specified integer by iteratively marking the multiples of each prime starting from 2.

Front

Can a prime number be negative?

Back

No, prime numbers are defined only within the set of natural numbers (positive integers).

Front

What is the difference between a prime number and a composite number?

Back

A prime number has exactly two distinct positive divisors (1 and itself), while a composite number has more than two positive divisors.