To find the length of a rectangle with an area of 16 cm², we need to know the width of the rectangle. If we assume that the width is a whole number, we can use trial and error to find possible pairs of length and width that have an area of 16 cm².
The factors of 16 are: 1, 2, 4, 8, and 16.
So the possible pairs of length and width are:
Length = 1 cm, Width = 16 cm
Length = 2 cm, Width = 8 cm
Length = 4 cm, Width = 4 cm
Length = 8 cm, Width = 2 cm
Length = 16 cm, Width = 1 cm
Out of these options, we can see that the pair of Length = 4 cm and Width = 4 cm gives an area of 16 cm². Therefore, the length of the rectangle is 4 cm.