Question

21m a dm
72m a mm
82dm a mm
53hm a m

Answer 1

21m a dm = 210
72m a mm = 72000
82dm a mm= 8200
53 hm a m= 5300

Answer 2

21 m a dm
21 m X 10 dm  = 210 dm.
-------------------------------
72 m a mm.
72 m X 1000 mm= 72000 mm
_______________________
82 dm a mm
82 dm X 100 mm  = 8200 mm.
_________________________
53 hm a m
53 hm X 100 m  = 5300 m.