SME
Grade 3 Math · Problem type
Use arrays to multiply
Use this for rows and columns: “6 rows of 4 chairs. How many chairs?”
Diagram
3 rows of 7: 3 × 7 = 21
This is an example. Type your own values to start a new problem.
Rows
×
In each row
=
Total
Formulas
3 × 7 = 21
Rows × in each row = total
Assumptions
•
Every row has the same number, and so does every column.
•
Rows × number in each row = total.
•
Turn the array and the total stays the same: 4 × 6 = 6 × 4.
Step-by-step
WE KNOW
Rows: 3
In each row: 7
FIND
total
Step 1 · Find total
3 × 7 = ?
Rows × in each row = total
Multiply the rows by the number in each row.
Count by 7s, 3 times: 7, 14, 21 → 21
Total = 21
Check
Put the numbers back in. Both sides should match.
3 × 7 = 21 ✓
Topic check
See what you know: 5 questions on this topic
New questions each time. Pass to mark it complete.
Refresh
Related lessons
Multiply and divide within 100
Main lesson
Use number lines to divide
Use this for equal jumps on a number line: “How many jumps of 5 to get to 30?”
Division: how many in each group?
Use this to share equally: “24 stickers shared by 4 friends. How many each?”
Division: how many equal groups?
Use this for “24 stickers, 6 on each page. How many pages?”
Solve multiplication and division equations
Use this for a number sentence with a box: 8 × ? = 48.
Divide by breaking apart
Use this for “72 chairs in 4 equal rows: how many in each row?” past the facts.