Divisibility Rules

Why is 1 neither prime or composite?

• This is a bad question because 1 is actually prime

• Because it is odd

• Because it only has 1 factor: itself.

• This is a bad question because 1 is actually composite

• It has only one array.

Choose the TWO correct answer.

All numbers ending in 5 have ________________

• 1 as a factor

• 5 as a factor

• 10 as a factor

• 3 as a factor

35 can be evenly divided by which number?

• 5
• 10
• 2
• All of the above

What is the divisibility rule for 3?

Read the answer choices carefully!

• Add up the digits. The sum must be even and divisible by 3.
• The digits must add up to 9.
• The last digit must be a 3.
• Add up the digits. The sum must be divisible by 3.

What is the divisibility rule for 5?

• The digits must add up to 10.
• The last digit needs to be a 5 or 0.
• The last digit can only be a 5.
• The sum of the digits need to be divisible by 5.

What are factors?

• number that are multiplied together to get a multiple.

• prime numbers

• composite numbers

• numbers that are added together

Any whole number is divisible by 2 if the ones digit is _____

• divisible by 9
• divisible by 3
• an even number
• 5 or 0