Assess Yourself

That is right! You have the correct answer.

Try again! 1 is always a factor for all numbers, but it is rarely the greatest common factor between 2 numbers.

Try again! The GCF can be any number; it can be 2, it can be 10 or more.

Try again! Unless you are comparing 0 to 0, 0 will never be the GCF. There will always be a number that is greater than 0 that will be the GCF.

That is right! You found the greatest common factor.

Try again! Look at the common factors 6 and 18. Then, circle the greatest common factor.

Try again! Make sure you are looking for the greatest common factor of 6 and 18.

Try again! After identifying the common factors of 6 and 18, you want to circle the greatest common factor.

Try again! You want to make sure your factor rainbow has the correct factors of 3 and 13. Then, identify the GCF.

That is right! One is the only factor both numbers have in common.

Try again! Go back and check to see if you have the correct common factors of 3 and 13.

Try again. A common factor has to be the same for both numbers.

Try again. Use a multiplication table or the factor rainbow strategy.

Try again. Think about what number times 1 equals 17 and continue from 1.

That is right! You found all the factors of 17.

You are close. Go back and make sure you have identified the correct factors of 17.

That is right! You found the correct answer.

Try again! Factors are numbers that are multiplied together.

Try again! Factors are numbers that are multiplied together.

You are close! Factors are numbers that are multiplied together.

Try again. 3 is a factor of 3. Think about if 3 goes into 23 evenly. The greatest common factor has to be the same for both numbers.

That is right! You found the greatest common factor of 3 and 23.

Try again! 23 is a factor for 23. Think about if 23 is a factor of 3.

Try again! Factors of zero are infinite. It’s not the greatest factor for 3 and 23

Try again! Use a multiplication table or the factor rainbow strategy.

Try again! Listing factors will always give more than one factor. Think about what times 1 will give you 19.

That is right! You found all the factors of 19.

Try again! Go back to your factor rainbow to make sure you have identified the correct factors of 19. 20 times anything wouldn’t equal 19.

Try again. 3 and 21 do share 1 as a factor. However, it is not the greatest factor.

Try again! Think about what times 21 would equal 3. 21 is not a factor of 3.

That is right! You found the greatest common factor of 3 and 21.

Try again! Think about what times 7 would equal 3. 7 is not a factor of 3.

Try again. Remember factors come in pairs. There’s a factor missing.

That is right! You found all the factors of 7.

Try again. Think about what times 7 equals 7.

Try again. Any number times zero is zero.

Try again. 2 is a factor of 4 and 12. However, it is not the greatest common factor.

Try again. 1 would be the least common factor of 4 and 12. Go back to identify the greatest common factor.

That is right! You found the greatest common factor of 4 and 12.

You are close. Go back to see what common factors 4 and 12 have. Next, choose the greatest common factors.