7km2 = 7 000 000m2

4ha = 40 000m2

8,5 ha = 85 000 m2

7000000m2; 40000m2; 85000m2

30 dm2 = 0,3 m2

300dm2 = 3m2

515dm2 = 5,15m2

7 km 2 = 7 000 000 m 2

4ha = 40 000 m 2

8,5 ha = 85 000  m 2

30 d m 2 = 0,3  m 2

300d m 2 = 3 m 2

515d m 2 = 5,15 m 2

8 d m 2 = 8 100 m 2 = 2 25 m 2 ; 1251 m 2 = 125 10000 m 2 = 1 80 m 2

a: 47 phút=\(\frac{47}{60}\) giờ

125 phút=\(\frac{125}{60}\) giờ=\(\frac{25}{12}\) giờ

235 giây=\(\frac{235}{3600}\) giờ=\(\frac{47}{720}\) giờ

49 giây\(=\frac{49}{3600}\) giờ

b: \(47dm^2=\frac{47}{100}m^2\)

\(124dm^2=\frac{124}{100}m^2=\frac{31}{25}m^2\)

\(1256\operatorname{cm}^2=\frac{1256}{10000}m^2=\frac{157}{1250}m^2\)

\(45\operatorname{cm}^2=\frac{45}{10000}m^2=\frac{9}{2000}m^2\)

c: 27cm=27/100m

125mm=125/1000m=1/8m

345dm=345/10m=69/2m

48dm=48/10m

d: \(43\left(gam\right)=\frac{43}{1000}\left(\operatorname{kg}\right)\)

\(165\left(gam\right)=\frac{165}{1000}\left(\operatorname{kg}\right)\)

a ) 3 10 ; 11 100 ; 213 1000 . b ) 7 100 ; 129 10000 c ) 521 1000 .