Draw a diagonal scale showing a single direct vernier to read centimetres. The scale is to represent 4 decimetres. Calculate and show the length of 2.20 dm and 57 mm.

Here's why:

• Scale Construction: You have correctly constructed a scale where 3 cm on the drawing represents 1 dm (10 cm) in reality. The total length of your scale represents 4 dm, as required (from the '3' mark to the leftmost '0' mark, plus the subdivided section).
• Decimeter Divisions: The main divisions to the right of '0' are correctly marked '1', '2', '3', representing decimeters.
• Centimeter Subdivisions: The leftmost section (from the main '0' mark to the left end) is correctly subdivided into 10 equal parts using the diagonal line method. These subdivisions are appropriately labeled '0', '2', '4', '6', '8', '10', allowing for reading in centimeters.
• Measurements:
  • The measurement of $2.20 \text{ dm}$ is correctly indicated from the '2' dm mark to the '2' cm mark (since $0.20 \text{ dm} = 2 \text{ cm}$).
  • The measurement of $57 \text{ mm}$ (which is $5.7 \text{ cm}$) is correctly indicated from the '0' mark to a point between the '5' and '6' cm marks in the subdivided section.

Your drawing accurately represents the required scale and demonstrates how to read the specified measurements.