Giải bài 2 trang 154 - SGk Toán lớp 5

Hướng dẫn:

$1km^2 = 100ha = 100hm^2 = 10\, 000dam^2 = 1\, 000\, 000m^2 \\ 1m^2 = 100dm^2 = 10 \, 000cm^2 = 1 \, 000 \, 000mm^2$

Bài giải:

a)

$1\text{m}^2 = 100\text{dm}^2 = 10\,000\text{cm}^2 = 1 \, 000 \, 000\text{mm}^2 \\ 1\text{ha} = 10\, 000 \text{m}^2 \\ 1\text{km}^2 =100\text{ha} = 1\, 000\, 000\text{m}^2$

b)

$1\text{m}^2 = 0,01\text{dam}^2 \\ 1\text{m}^2 = 0,0001\text{hm}^2 =0,0001\text{ha} \\ 1\text{m}^2 =0,000001\text{km}^2 \\ 1\text{ha} = 0,01\text{km}^2 \\ 4\text{ha} = 0,04\text{km}^2$