Reveal Math Grade 4, Unit 5: Factors and Multiples
In this unit, your child finds all the factor pairs for whole numbers up to 100, lists multiples, and sorts numbers as prime or composite. It draws on the multiplication and division facts from the previous unit, and those factors become the tool for finding equivalent fractions in the unit on fraction equivalence that follows.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 5?
- Listing every factor pair of a number up to 100, telling factors from multiples, and sorting numbers as prime or composite. Learn more about finding factors and multiples up to 100: Finding factors and multiples up to 100 · Learn more about spotting prime numbers
Sample questions to try together
These are real questions from our practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
4 × 9 = 36. Which sentence is true?
- 4 is a multiple of 36.
- 36 is a multiple of 4, but not of 9.
- 36 is a multiple of both 4 and 9.
How you can help
- Arrange 36 blocks, crackers, or cards into every rectangle you can, and write down each factor pair, including 6 × 6.
- Skip-count by 7s on a walk, naming the multiples of 7 up to 70, then ask your child whether 49 is one of them and how they know.
- Play "prime or composite" with page numbers in a book, and ask your child to prove a number is composite by naming one of its factor pairs.
Where kids can get stuck
- Missing factor pairs in the middle, such as finding 1 × 48 and 2 × 24 but not 6 × 8.
- Mixing up factors and multiples, calling 12 a factor of 3 when it is really a multiple of 3.
- Thinking every odd number is prime, so 15 and 21 get sorted as prime even though 15 = 3 × 5.
Practice makes perfect
Bobby's Math Club has practice problems that adapt to your child’s level, each with a detailed explanation and an easy-to-follow video, so your child can build confidence in these skills one step at a time.
Words your child will hear
- factor
- A number multiplied by another number to make a product, like 4 and 6 in 4 × 6 = 24.
- factor pair
- Two numbers that multiply to make a given number, like 4 and 9 for 36.
- multiple
- The product of a number and a whole number, like 6, 9, and 12 for 3.
- prime number
- A whole number greater than 1 with exactly two factors, 1 and itself, such as 7.
- composite number
- A whole number with more than two factors, such as 9 or 12.
- divisible
- Able to be divided by a number with no remainder, as 24 is divisible by 6.
- product
- The answer to a multiplication problem.
Ready to build your child’s confidence with factors and multiples?
In Bobby's Math Club, your child practices these skills at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free.
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Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
Which math standards does Reveal Math Grade 4 Unit 5 cover?
Reveal Math Grade 4 Unit 5 covers this math standard. Each one links to what it means, sample questions, and teaching strategies.
- 4.OA.B.4: Find factors and multiples up to 100, and spot prime numbers.
For teachers: Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence. Learn how Bobby's Math Club can help your students grow.