As a driver, I am amazed by the confidence of people who walk on the road with their backs to oncoming traffic. If you have to copy answers to homework questions, tests or examinations will trip you. We first identify some numbers and quantities. After this, perhaps, we can speak about them, all without doing any arithmetic. There is more to mathematics than just doing arithmetic.
Height is a quantity.
A building has a height. So has an elephant. The elephant also has a weight and a width or a girth. A rectangle has a length, a width and an area. A closed box has a width, a length, a height and a volume.