**Definitions:**

**Double Square Foot** (abbreviation: **ft4**): is an imperial unit and U.S. customary unit (non-SI, non-metric) of area moment of inertia, a geometrical property of an area which reflects how its points are distributed with regard to an arbitrary axis.

**Double Square Inch** (abbreviations: **in4, or in 4**): is a unit in the (British) imperial and United States customary systems of measurement of area moment of inertia, a geometrical property of an area which reflects how its points are distributed with regard to an arbitrary axis.

## How to Convert Double Square Feet to Double Square Inches

*Example: How many double square inches are equivalent to 99.54 double square feet?*

As;

1 double square feet = 20736 double square inches

99.54 double square feet = Y double square inches

Assuming Y is the answer, and by criss-cross principle;

Y equals 99.54 times 20736 over 1

(i.e.) Y = 99.54 * 20736 / 1 = 2064061.44 double square inches

Answer is: 2064061.44 double square inches are equivalent to 99.54 double square feet.

*Practice Question: Convert the following units into in4:*

N.B.: After working out the answer to each of the next questions, click adjacent button to see the correct answer.

( i ) 51.31 ft4

( ii ) 61.58 ft4

( iii ) 67.73 ft4