Topic 8 of 8
Equal groups and arrays
Step 4 · Place value to 1,000 topics
Find the total of equal groups, arrange things in rows and columns, and write the total as a sum of equal numbers.
Equal groups
Equal groups all have the same number in them. 3 plates with 4 grapes on each is 3 equal groups of 4. Count by 4s to find the total: 4, 8, 12.
Rows and columns
An array sets things out in straight rows and columns, like eggs in a box or chairs in a hall. Each row has the same number, and so does each column.
Turning an array round swaps rows and columns but not the total: 3 rows of 5 and 5 rows of 3 are both 15.
A rectangle can be split into rows and columns of equal squares. Count the squares to find the total.
Writing an array as a sum
Add one row at a time. 3 rows of 5 is 5 + 5 + 5 = 15. You can also add the columns: 3 + 3 + 3 + 3 + 3 = 15.
Example: Rows as a sum
A garden has 4 rows of 3 plants. How many plants? Write a sum.
- Each row has 3 plants.
- 4 rows: 3 + 3 + 3 + 3.
- Count by 3s: 3, 6, 9, 12.
Answer3 + 3 + 3 + 3 = 12 plants
Arrays are the start of multiplication, which comes in the next step: 4 rows of 3 is 4 × 3.
Try it yourself
Work each one on paper first, then open the answer to check.
4 bags with 5 apples in each. How many apples?
Show answer
20: 5 + 5 + 5 + 5.
Write a sum for an array of 2 rows of 6.
Show answer
6 + 6 = 12.
An array has 5 rows and 4 columns. How many things are in it?
Show answer
20.
Is 3 rows of 4 the same total as 4 rows of 3?
Show answer
Yes, both are 12.
A rectangle is split into 2 rows of 3 equal squares. How many squares?
Show answer
6.