There isn't any one general answer. It depends on what unit you want to convert to what other unit.
You can't convert that. In general, you can only convert from one unit to another of the same kind, for example, one unit of mass to another unit of mass.
You can't convert that. You can convert from one linear unit to another linear unit, or from one square unit to another square unit, but not between linear units and square units.
Since a meter is a unit of length and a hectar is a unit of area, the two units are incompatible - you can't convert one to the other.
You don't. One is a unit of length and the other a unit of area.
You can't convert that. You can convert from one unit of length to another, or from one unit of area to another, but you can't convert between units of length and area.
You don't really "convert a unit of measurement"; you convert from one unit to another. The two - "from" and "to" are always required.
That means that if you have a measurement in one unit, you convert it to another unit. For example, if a measurement is given in millimeters, you may need to convert it to meters.
There isn't any one general answer. It depends on what unit you want to convert to what other unit.
You can't convert that. In general, you can only convert from one unit to another of the same kind, for example, one unit of mass to another unit of mass.
You can't convert that. You can convert from one linear unit to another linear unit, or from one square unit to another square unit, but not between linear units and square units.
You can't convert that. You can convert from one linear unit to another linear unit, or from one square unit to another square unit, but not between linear units and square units.
Look in the link below.
By dividing the multiple by the root unit.
Since a meter is a unit of length and a hectar is a unit of area, the two units are incompatible - you can't convert one to the other.
Dimensional analysis
A conversion factor