For an answer to be complete, the units need to be specified. Why?
Importance of unit in measurement
Unit is an important part of any measurement. A measurement is complete only when the magnitude (including unit) and direction (if needed as in the case of vectors) are completely specified. Without mentioning the unit, a measurement is completely non-understandable. For example, if a person asks a shopkeeper to give him/her 5 meters of cloth, s/he must mention the unit, “meter”. Otherwise, the shopkeeper will not understand whether the person wants 5 feet, 5 yards or 5 meters of cloth.
Therefore, for a clearly understandable message one must mention a specific unit of the quantity.