Giải Bài 2 trang 47 Vở thực hành Toán 5

Lời giải

a) Ta có $1 \text{ km}^2 = 100 \text{ ha}$ nên:

$5 \text{ km}^2 = 5 \times 100 = 500 \text{ ha}$

b) Ta có $100 \text{ ha} = 1 \text{ km}^2$ nên:

$600 \text{ ha} = 600 : 100 = 6 \text{ km}^2$

c)

- $2 \text{ m}^2 \ 5 \text{ dm}^2$: vì $1 \text{ m}^2 = 100 \text{ dm}^2$ nên $2 \text{ m}^2 = 200 \text{ dm}^2$. Do đó $2 \text{ m}^2 \ 5 \text{ dm}^2 = 200 + 5 = 205 \text{ dm}^2$.

- $12 \text{ m}^2 = 12 \times 100 = 1\,200 \text{ dm}^2$.

- $2\,500 \text{ dm}^2 = 2\,500 : 100 = 25 \text{ m}^2$.

- $40 \text{ cm}^2 \ 4 \text{ mm}^2$: vì $1 \text{ cm}^2 = 100 \text{ mm}^2$ nên $40 \text{ cm}^2 = 4\,000 \text{ mm}^2$. Do đó $40 \text{ cm}^2 \ 4 \text{ mm}^2 = 4\,000 + 4 = 4\,004 \text{ mm}^2$.

- $6 \text{ dm}^2 = 6 \times 100 = 600 \text{ cm}^2$.

- $900 \text{ cm}^2 = 900 : 100 = 9 \text{ dm}^2$.

- $615 \text{ dm}^2$: vì $600 \text{ dm}^2 = 6 \text{ m}^2$ nên $615 \text{ dm}^2 = 6 \text{ m}^2 \ 15 \text{ dm}^2$.

Đáp số