Để điền số thập phân thích hợp vào chỗ trống, chúng ta cần thực hiện một số phép chuyển đổi giữa các đơn vị đo diện tích.

a. \(6 \, \text{dm}^2 42 \, \text{cm}^2\)
1 dm² = 100 cm²
=> \(6 \, \text{dm}^2 = 600 \, \text{cm}^2\)
=> \(6 \, \text{dm}^2 42 \, \text{cm}^2 = 600 \, \text{cm}^2 + 42 \, \text{cm}^2 = 642 \, \text{cm}^2\)
=> \(642 \, \text{cm}^2 = 6,42 \, \text{dm}^2\)

b. \(1 \, \text{km}^2 5 \, \text{m}^2\)
1 km² = \(1,000,000 \, \text{m}^2\)
=> \(1 \, \text{km}^2 = 1,000,000 \, \text{m}^2\)
=> \(1 \, \text{km}^2 5 \, \text{m}^2 = 1,000,000 \, \text{m}^2 + 5 \, \text{m}^2 = 1,000,005 \, \text{m}^2\)

c. \(37 \, \text{cm}^2 6 \, \text{mm}^2\)
1 cm² = 100 mm²
=> \(37 \, \text{cm}^2 = 3700 \, \text{mm}^2\)
=> \(37 \, \text{cm}^2 6 \, \text{mm}^2 = 3700 \, \text{mm}^2 + 6 \, \text{mm}^2 = 3706 \, \text{mm}^2\)
=> \(3706 \, \text{mm}^2 = 37,06 \, \text{cm}^2\)

d. \(8500 \, \text{km}^2\)
1 km² = \(1,000,000 \, \text{m}^2\)
=> \(8500 \, \text{km}^2 = 8500 \times 1,000,000 \, \text{m}^2 = 8,500,000,000 \, \text{m}^2\)

Tóm tắt kết quả:
a. \(6,42 \, \text{dm}^2\)
b. \(1,000,005 \, \text{m}^2\)
c. \(37,06 \, \text{cm}^2\)
d. \(8,500,000,000 \, \text{m}^2\)