Let's solve the questions one by one, converting all measurements into the required unit.

1. 12 hm + 8 dam + 7 m = ...... m

   • $1 \, \text{hm} = 100 \, \text{m}$
   • $1 \, \text{dam} = 10 \, \text{m}$

   Calculation: $12 \, \text{hm} = 12 \times 100 = 1200 \, \text{m}$ $8 \, \text{dam} = 8 \times 10 = 80 \, \text{m}$ $\text{Total} = 1200 \, \text{m} + 80 \, \text{m} + 7 \, \text{m} = 1287 \, \text{m}$ Answer: 1287 m

2. 6 km + 4 hm + 6 dam = ...... dam

   • $1 \, \text{km} = 100 \, \text{dam}$
   • $1 \, \text{hm} = 10 \, \text{dam}$

   Calculation: $6 \, \text{km} = 6 \times 100 = 600 \, \text{dam}$ $4 \, \text{hm} = 4 \times 10 = 40 \, \text{dam}$ $\text{Total} = 600 \, \text{dam} + 40 \, \text{dam} + 6 \, \text{dam} = 646 \, \text{dam}$ Answer: 646 dam

3. 1 m + 4 dm + 6 cm = ...... mm

   • $1 \, \text{m} = 1000 \, \text{mm}$
   • $1 \, \text{dm} = 100 \, \text{mm}$
   • $1 \, \text{cm} = 10 \, \text{mm}$

   Calculation: $1 \, \text{m} = 1000 \, \text{mm}$ $4 \, \text{dm} = 4 \times 100 = 400 \, \text{mm}$ $6 \, \text{cm} = 6 \times 10 = 60 \, \text{mm}$ $\text{Total} = 1000 \, \text{mm} + 400 \, \text{mm} + 60 \, \text{mm} = 1460 \, \text{mm}$ Answer: 1460 mm

4. 3 km + 4 hm + 3 dam = ...... m

   • $1 \, \text{km} = 1000 \, \text{m}$
   • $1 \, \text{hm} = 100 \, \text{m}$
   • $1 \, \text{dam} = 10 \, \text{m}$

   Calculation: $3 \, \text{km} = 3 \times 1000 = 3000 \, \text{m}$ $4 \, \text{hm} = 4 \times 100 = 400 \, \text{m}$ $3 \, \text{dam} = 3 \times 10 = 30 \, \text{m}$ $\text{Total} = 3000 \, \text{m} + 400 \, \text{m} + 30 \, \text{m} = 3430 \, \text{m}$ Answer: 3430 m

5. 8 hm + 5 dam + 10 dm = ...... m

   • $1 \, \text{hm} = 100 \, \text{m}$
   • $1 \, \text{dam} = 10 \, \text{m}$
   • $1 \, \text{dm} = 0.1 \, \text{m}$

   Calculation: $8 \, \text{hm} = 8 \times 100 = 800 \, \text{m}$ $5 \, \text{dam} = 5 \times 10 = 50 \, \text{m}$ $10 \, \text{dm} = 10 \times 0.1 = 1 \, \text{m}$ $\text{Total} = 800 \, \text{m} + 50 \, \text{m} + 1 \, \text{m} = 851 \, \text{m}$ Answer: 851 m

Let me know if you need further explanation or want me to continue solving the remaining questions. Here are five questions related to this topic:

1. What are the conversion factors between kilometers, hectometers, and meters?
2. How many centimeters are there in one meter?
3. What is the relationship between decimeters and millimeters?
4. How do you convert from kilometers to meters and then to centimeters?
5. Can you convert 15 hectometers directly to centimeters?

Tip: Always break down multi-unit conversions into smaller, simpler steps for clarity.