An Array is an arrangement of a set of numbers or objects in rows and columns.

More About Array

An array is normally used to write multiplication and division number sentences.
A multiplication array can easily be expressed as a repeated addition.
A division array can easily be expressed as a repeated subtraction.

Examples of Array

The dots in the above figure are arranged in 4 rows and 7 columns. It can also be written as 7 × 4 = 7 + 7 + 7 + 7 = 28The cubes in the above figure are arranged in 4 rows and 9 columns. It can also be written as 9 × 4 = 9 + 9 + 9 + 9 = 36.

Video Examples: How to Write Math Arrays : Principles of Math

Solved Example on Array

Ques: Greg shaded the cells on a grid to make a rectangle, as shown. Which number sentence could be used to determine the total number of cells shaded to make the rectangle?

Choices:

A. 4 × 6 = 24
B. 1 × 25 = 25
C. 5 × 6 = 30
D. 30 × 3 = 90
Correct Answer: C

Solution:

Step 1: On the grid shown, the rectangle is 5 rows wide with 6 cells shaded in each row and there are 30 cells shaded in all.
Step 2: Number of rows × Number of cells shaded in each row = Total number of cells that make the rectangle
Step 3: 5 × 6 = 30 [Substitute the values.]
Step 4: So, the number sentence that could be used to determine the total number of cells shaded to make the rectangle is 5 × 6 = 30.