câu1
1km=...............cm 1000m=..............km 60cm=..............dm
9m=................dm 400cm=..............m 1dm=...............m
8km=..............m 5dm=............cm 9000m=............km
câu2
458 + 123= 569+ 569= 642+123=
câu3
49cm+82m= 44m+1cm= 22m+22m+22m=