Understanding Counterexamples

Which number serves as a counterexample to the statement that all prime numbers are odd?

• 7

• 2

• 5

• 3

What is the main reason the difference between two odd prime numbers is usually even?

• Odd numbers always have even differences.

• The sum of two odd numbers is even.

• Prime numbers are always odd.

• The difference between two odd numbers is even.

Which pair of prime numbers provides a counterexample to the statement that the difference between two prime numbers is always even?

• 11 and 17

• 3 and 7

• 5 and 23

• 2 and 5

What is the last digit of the square number that disproves the statement that all square numbers end in 1, 4, 6, or 9?

• 5

• 9

• 4

• 1

Which of the following is a square number that does not end in 1, 4, 6, or 9?

• 25

• 36

• 16

• 9