Compare and Order: 50mm, 0.2dm, 4cm, and 0.005m from Smallest to Largest

To solve this problem, we need to convert each measurement to meters and then order them:

• Convert 50 mm to meters:
  Since 1 meter = 1000 millimeters, we have:
  $\frac{50 \text{ mm}}{1000} = 0.05$ meters
• Convert 0.2 dm to meters:
  Since 1 meter = 10 decimeters, we have:
  $\frac{0.2 \text{ dm}}{10} = 0.02$ meters
• Convert 4 cm to meters:
  Since 1 meter = 100 centimeters, we have:
  $\frac{4 \text{ cm}}{100} = 0.04$ meters
• Convert 0.005 m to meters:
  It is already given in meters:
  $0.005$ meters

Now, let's compare the values in meters:
- 0.005 meters
- 0.02 meters (from 0.2 dm)
- 0.04 meters (from 4 cm)
- 0.05 meters (from 50 mm)

Order them from smallest to largest:
1. $0.005$ meters
2. $0.02$ meters
3. $0.04$ meters
4. $0.05$ meters

Therefore, the order from smallest to largest in their original units is:
1. $0.005$ m
2. $0.2$ dm
3. $4$ cm
4. $50$ mm

Therefore, the correct ordering is choice 4 which matches:
$0.005$ m, $0.2$ dm, $4$ cm, $50$ mm.