Using an Array to Multiply by 4
Using an Array to Multiply by 4 is a Grade 3 math skill from Eureka Math connecting arrays to multiplication by 4. An array with n rows and 4 columns represents the expression n × 4. Students skip-count by 4 across each row to find the total. For example, 3 × 4 is modeled as 3 rows of 4, skip-counting 4, 8, 12. This visual-physical approach makes the multiplication table for 4 concrete before students move to memorization, helping third graders understand what multiplication means before relying on abstract recall.
Key Concepts
To find the product of a number multiplied by 4 using an array, you can represent the problem with an array that has that number of rows and 4 columns. The total number of objects in the array is the product, which can be found by skip counting by 4 for each row. The expression $n \times 4$ corresponds to the total after counting $n$ rows.
Common Questions
How does an array model multiplication by 4?
An array with n rows and 4 columns represents n × 4. Each row contains 4 objects, and counting all objects (or skip-counting by 4 per row) gives the product.
What does skip-counting by 4 mean?
Skip-counting by 4 means counting in jumps of 4: 4, 8, 12, 16, 20. Each jump represents one row of 4 in the array.
How do you use an array to find 6 × 4?
Draw 6 rows with 4 circles in each. Skip-count by 4 six times: 4, 8, 12, 16, 20, 24. The product is 24.
Why use arrays to learn multiplication by 4?
Arrays make the structure of multiplication visible. Students can see that 6 × 4 means 6 equal groups of 4, not just a memorized fact, building conceptual understanding.
In which textbook is Using an Array to Multiply by 4 taught?
This skill is taught in Eureka Math, Grade 3.