# A Susan B. Anthony dollar coin has a diameter of 26.50 millimeters. What is the area of the coin to the nearest hundredth?

Jan 27, 2017

$551.55 m {m}^{2}$

#### Explanation:

Coin's diameter is 26.50 millimetres

using the unit of measurement of $m m$ for millimetres

So its radius is $\frac{1}{2} \times 26.50 = 13.25 m m$

Area of a circle is $\pi \times {\left(\text{radius")xx("radius") -> pi("radius}\right)}^{2}$

So the area is $\pi \times 13.25 \times 13.25$

Using a calculator this is: 551.54586....

For the nearest hundredth we have the cut off point:

$551.54 \textcolor{red}{|} 586. . .$
$\text{ } \textcolor{red}{\uparrow}$
$\textcolor{red}{\text{cut off point}}$

The digit immediately to the right of the cut of point is classified as 5 or more. So the digit to the left of the cut off point is raised by 1 and all those to the right made into 0

$551.55 \textcolor{red}{|} 000. .$
$\text{ } \textcolor{red}{\uparrow}$
$\textcolor{red}{\text{The 4 changed to 5}}$