Arrays for multiplication and division

Worked solution

1. 1

   Count rows and dots in each row.

   $4\times 5=20$

   The picture has four equal rows of five dots.

2. 2

   Use the columns for the reversed product.

   $5\times 4=20$

   There are also five equal columns of four dots.

3. 3

   Divide by the number of rows.

   $20÷4=5$

   Sharing the total among four rows gives five dots per row.

4. 4

   Divide by the dots in each row.

   $20÷5=4$

   Grouping the dots in fives gives four rows.

Worked solution

1. 1

   Split the twelve dots in each row.

   $12=10+2$

   Every row is separated into a group of ten and a group of two.

2. 2

   Count the two rectangular parts.

   $\begin{array}{rl}3\times 10& =30\\ 3\times 2& =6\end{array}$

   Both parts still have three equal rows.

3. 3

   Combine their totals.

   $3\times 12=30+6=36$

   The two parts cover the original array exactly once.