Bernard found a copper coin with a radius of 9 millimeters. What is the coin’s area?
Use 3.14 for . If necessary, round your answer to the nearest hundredth.
Square millimeters

To find the area of the coin, we can use the formula for the area of a circle: . Here, is the radius of the coin, which is 9 mm. Plugging in the values, we get:

So, the area of the coin is approximately 254.34 square millimeters.

Now let’s talk about copper coins! Traditionally, copper was widely used in currency due to its durability and resistance to corrosion. In many cultures, copper coins became a symbol of trade, allowing people to buy and sell goods. Even today, the penny in the United States is primarily made of zinc, but it still has a copper coating, linking back to its historical roots.

If you’re working on problems involving area, it’s easy to mix up the radius and diameter. Remember: the diameter is twice the radius! Always double-check your values to avoid any mix-ups. When using the area formula, it’s helpful to keep in mind the units (square millimeters in this case) and don’t forget to square your radius before multiplying by !