Find the area of a rectangle in different ways if one side is 3 cm and the other is 2 cm 8 mm.

The area is the product of the length and width of a polygon, in this case a rectangle with sides 3 cm and 2 cm 8 mm.
That is, in order to find the area of ​​a given rectangle, you need to multiply it 3 cm by 2 cm 8 mm. This can be done in two ways, and both answers will be the same and correct.
First way: convert all values ​​to mm. 1 cm – 10 mm.
This means: 3 cm = 3 * 10 = 30 mm.
2 cm 8 mm = 2 * 10 + 8 = 28 mm.
We find the area: 30 * 28 = 840 mm².
In order to convert it to cm, you need to divide this number by 100 (since the values ​​are square).
We get: 840: 10 = 8.4 cm².
Second way: convert all values ​​to cm.
2 cm 8 mm = 2.8 cm.
We find the area: 2.8 * 3 = 8.4 cm².
Answer: 8.4 cm².