Factors, Highest Common Factors & Primes

Find the factors, highest common factor, or identify primes.

All objectives

Foundation

16 web questions

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  1. Write all the factors of $12$.
  2. Write all the factors of $18$.
  3. Write all the factors of $20$.
  4. Write all the factors of $24$.
  5. Is $4$ a factor of $28$?
  6. Is $5$ a factor of $27$?
  7. Is $6$ a factor of $42$?
  8. Circle the factors of $15$: $1, 2, 3, 5, 6, 15$.
  9. Circle the factors of $16$: $1, 2, 4, 5, 8, 16$.
  10. List the common factors of $12$ and $18$.
  11. List the common factors of $8$ and $20$.
  12. Find the highest common factor of $12$ and $18$.
  13. Find the highest common factor of $8$ and $20$.
  14. Is $11$ prime or composite?
  15. Is $15$ prime or composite?
  16. Complete: the highest common factor of $9$ and $12$ is $\square$.

Proficient

16 web questions

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  1. Write all the factors of $30$.
  2. Write all the factors of $36$.
  3. Write all the factors of $45$.
  4. List the common factors of $18$ and $24$.
  5. List the common factors of $20$ and $30$.
  6. Find the highest common factor of $18$ and $24$.
  7. Find the highest common factor of $20$ and $30$.
  8. Find the highest common factor of $27$ and $36$.
  9. Is $29$ prime or composite?
  10. Is $39$ prime or composite?
  11. Which is greater: the highest common factor of $18$ and $24$, or the highest common factor of $14$ and $21$?
  12. Fill in the blank: the highest common factor of $16$ and $24$ is $\square$.
  13. Fill in the blank: a common factor of $24$ and $36$ is $\square$.
  14. Is $9$ a factor of $45$?
  15. Is $7$ a factor of $54$?
  16. A baker arranges $18$ muffins and $24$ cookies into equal groups with no leftovers. What is the greatest number of groups possible?

Excellence

12 web questions

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  1. A student says the highest common factor of $18$ and $30$ is $6$. Are they correct? Explain.
  2. A student says $21$ is prime because it is odd. Are they correct? Explain.
  3. Write the first 4 common factors of $24$ and $36$.
  4. Find the highest common factor of $42$ and $56$.
  5. Find the highest common factor of $48$ and $60$.
  6. Find the highest common factor of $54$ and $72$.
  7. Which numbers are prime: $17, 21, 23, 27, 31$?
  8. Which does not belong: $2, 3, 5, 9, 11$?
  9. Fill in the blank: the highest common factor of $a$ and $18$ is $6$ when $a=\square$.
  10. Fill in both blanks: two common factors of $32$ and $40$ are $\square$ and $\square$.
  11. Which is greater: the highest common factor of $24$ and $32$, or the highest common factor of $27$ and $45$? Show enough working to justify.
  12. Is $35$ a factor of $140$? Is it the highest common factor of $140$ and $105$? Explain.