`a) 25m = 250 dm`
vì `1 m = 10 dm` nên `25 m = 25 xx 10 = 250 dm`
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`125 dm= 1250 cm`
Vì `1 dm = 10 cm` nên `125 dm = 125 xx 10 = 1250 cm`
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`200 cm =2000mm`
Vì 1 cm = 10 mm nên `200 cm = 200 xx 10 = 2000mm`
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`b)`
`60m = 6dam`
vì `1 m = 10 dam` nên ` 60m = 60 : 10 = 6dam`
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`500 m= 5hm`
vì `1 hm = 100m` nên `500 m = 500 : 100 = 5hm`
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`13 000m = 13km`
vì `1 km = 1000 m` nên` 13 000 m = 13000 : 1000 = 13km`
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`c)``1mm =0,1cm`
vì `1 cm = 10mm` nên `1mm = 1 : 10= 1/10 = 0,01cm`
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`1cm = 0,1 dm`
Vì `1 dm = 10cm` nên `1 cm = 1 : 10 = 1/10 = 0,1dm`
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`1dm = 0,1 m`
Vì `1m = 10dm` nên `1dm = 1 : 10 = 1/10 = 0,1 m`
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