Measurement of an area: if the side of the tile if <i>l</i>, the number of tiles is N<sub><i>l</i></sub>, the approximate area of the surface is N<sub><i>l</i></sub>×<i>l<sup>d</sup></i> where <i>d</i> is the dimension (here <i>d</i> = 2); the real area is π ≈ 3.14 cm².
Christophe Dang Ngoc Chan (<a href="//commons.wikimedia.org/wiki/User:Cdang" title="User:Cdang">cdang</a>)
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>