$\text{Câu 2:}$

$\text{12,5 dm = 125 cm}$

$\text{31,06 m = 3106 cm}$

$\text{0,348 m = 34,8 cm}$

$\text{0,782 dm = 7,82 cm}$

$\text{Câu 3:}$

$\text{7,35 yến = 73,5 kg}$

$\text{42,39 tạ = 4239 kg}$

$\text{5,0123 tấn = 5012,3 kg}$

$\text{0,061 tạ = 6,1 kg}$

$\text{Câu 4:}$

$\text{7,2 dm² = 720 cm²}$

$\text{14,31 dm² = 1431 cm²}$

$\text{0,045 dm² = 4,5 cm²}$

$\text{30,0345 dm² = 3003,45 cm²}$

$\text{Câu 5:}$

$\text{a)}$

$\text{15 m 8 cm = 15,08 m}$

$\text{12 tấn 6 kg = 12,006 tấn}$

$\text{56 dm² 21 cm² = 56,21 dm²}$

$\text{6 m² 5 cm² = 6,0005 m²}$

$\text{b)}$

$\text{29,83 m = 29 m 83 cm}$

$\text{13,5 m² = 13 m² 50 dm²}$

`2)`

`12,5` dm `= 125` cm

`31,06` m `= 3106` cm

`0,348` m `= 34,8` cm

`0,782` dm `= 7,82` cm

`3)`

`7,35` yến `= 73,5` kg

`42,39` tạ `= 4239` kg

`5,0123` tấn `= 5012,3` kg

`0,061` tạ `= 6,1` kg

`4)`

`7,2` dm$^2$ `= 720` cm$^2$

`14,31` dm$^2$ `= 1431` cm$^2$

`0,045` dm$^2$ `= 4,5` cm$^2$

`30,0345` dm$^2$ `= 3003,45` cm$^2$

`5)`

`a)15` m `8` cm `= 15,08` m

`12` tấn `6` kg `= 12,006` tấn

`56` dm$^2$ `21` cm$^2$ `= 56,21` dm$^2$

`6` m$^2$ `5` cm$^2$ `= 6,0005` m$^2$

`b)29,83` m `= 29` m `83` cm

`13,5` m$^2$ `= 13` m$^2$ `50` dm$^2$