Lesson 2 of 10 · Grades 3 to 4
Practice: Arrays and the commutative property
Arrays have rows and columns, and the turn-around rule lets you swap the two factors. These ten questions practise both, and a few ask you to explain your thinking.
How to use this page
This page gives you ten more questions on the same idea as the lesson "Arrays and the commutative property". Work through them at your own speed. Write your answer down or say it out loud before you open the answer box, so you give yourself a real chance to think.
If a question feels hard, go back to the lesson and look at the worked example again. Getting a question wrong is useful; it shows you the part that needs one more look.
Practice questions
Answer all ten questions in your notebook or in your head. Then open each answer to check your work.
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An array has 2 rows with 7 stars in each row. How many stars are there?
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14 stars. 2 × 7 = 14.
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Write the turn-around fact for 6 × 3 and solve it.
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3 × 6 = 18. The product is the same as 6 × 3.
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An egg tray is arranged in 4 rows of 5. How many eggs does it hold?
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20 eggs. 4 × 5 = 20.
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What is 7 × 8?
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56.
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A window has 6 rows with 4 panes in each row. How many panes are there?
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24 panes. 6 × 4 = 24.
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Is 5 × 6 equal to 6 × 5? Explain.
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Yes. Both equal 30, because turning an array around does not change the number of dots.
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An array has 9 rows and 9 columns. How many dots does it hold?
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81 dots. 9 × 9 = 81.
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Turn around 12 × 3 and solve the new fact.
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3 × 12 = 36. The answer matches 12 × 3.
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A wall is built from 8 rows of 8 tiles. How many tiles does it use?
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64 tiles. 8 × 8 = 64.
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A car park has 10 rows with 4 spaces in each row. How many spaces are there? Write the turn-around fact too.
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40 spaces. 10 × 4 = 40, and the turn-around fact is 4 × 10 = 40.