Definition
Square number
A square number is the product of a whole number multiplied by itself.
What it means
Pick a whole number and use it twice as the factors. The product is a square number. You can also picture that many dots in a perfect square array: 7 rows of 7 dots make 49, so 49 is a square number.
Remember it
Same number of rows and columns means the total is a square number.
Example
49 is a square number because 7 × 7 = 49, written 7² = 49. A 7-by-7 array contains exactly 49 items.
Watch for
42 is not a square number because no whole number multiplied by itself equals 42.
Common mix-up
Squaring a number is not doubling it: 7² means 7 × 7, not 7 + 7.
Exact meaning
A square number is a number of the form n × n, or n², where n is a whole number. Square numbers can be arranged as square arrays with the same number of rows and columns; examples include 0, 1, 4, 9, 16, 25, and 36.