1 cm2 = 100 mm2 1 dm2 = 100 cm2 1 m2 = 10 000 cm2 1 km2 = 1 000 000 m2

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a)

$1{\text{cm}}^2=1\text{cm}\cdot 1\text{cm}=10\text{mm}\cdot 10\text{mm}=\underline{100}{\text{mm}}^2$    

$9{\text{cm}}^2=9\cdot \underset{100{\text{ mm}}^2}{\underbrace{1{\text{cm}}^2}}=9\cdot 100{\text{mm}}^2=\underline{900}{\text{mm}}^2$    

$5,2{\text{cm}}^2=5,2\cdot \underset{100{\text{ mm}}^2}{\underbrace{1{\text{cm}}^2}}=5,2\cdot 100{\text{mm}}^2=\underline{520}{\text{mm}}^2$  

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b)  

$1{\text{dm}}^2=1\text{dm}\cdot 1\text{dm}=10\text{cm}\cdot 10\text{cm}=\underline{100}{\text{cm}}^2$    

$17{\text{dm}}^2=\underline{1700}{\text{cm}}^2$  

$4,3{\text{dm}}^2=\underline{430}{\text{cm}}^2$   

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c)

$1{\text{m}}^2=1\text{m}\cdot 1\text{m}=100\text{cm}\cdot 100\text{cm}=\underline{10000}{\text{cm}}^2$    

$7{\text{m}}^2=\underline{70000}{\text{cm}}^2$   

$2,5{\text{m}}^2=\underline{25000}{\text{cm}}^2$   

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d)

$1{\text{km}}^2=1\text{km}\cdot 1\text{km}=1000\text{m}\cdot 1000\text{m}=\underline{1000000}{\text{m}}^2$    

$50{\text{km}}^2=\underline{50000000}{\text{m}}^2$  

$8,5{\text{km}}^2=\underline{8500000}{\text{m}}^2$