how do you calculate metric surfaces?

not sure what you mean.

are you finding areas of surfaces that have metric units?
are you converting between units of area in the metric system?

give a specific example or problem.

To calculate the area of metric surfaces, you need to know the formulas specific to the shape you are dealing with. Here are the formulas for some common metric shapes:

1. Rectangles and Squares:
- Area of a rectangle = length x width
- Area of a square = side x side (or side^2)

2. Triangles:
- Area of a triangle = (base x height) / 2

3. Circles:
- Area of a circle = π x radius^2 (where π is approximately 3.14159)

4. Trapezoids:
- Area of a trapezoid = [(sum of the parallel sides) / 2] x height

5. Parallelograms:
- Area of a parallelogram = base x height

Once you have the measurements for the respective sides or dimensions of the shape you are dealing with, you can substitute these values into the appropriate formula to calculate the area. Remember to use consistent units (e.g., square meters, square centimeters) throughout the calculation.

If you are looking to convert between units of area in the metric system, you can use the conversion factors given below:

1 square meter (m^2) = 10,000 square centimeters (cm^2)
1 square meter (m^2) = 1,000,000 square millimeters (mm^2)
1 square centimeter (cm^2) = 100 square millimeters (mm^2)

To convert from one unit to another, multiply or divide the original measurement by the appropriate conversion factor.