If you have to copy answers to homework questions, tests or examinations will trip you. Our next aim is to show how everyday words should be used in mathematics to describe numbers and quantities - their use here is close to their everyday meanings. For example, we can say if a number or quantity is known or not, changing or not, constant or not, increasing, decreasing, shrinking, growing, confidential or embarrassing, top-secret or simply forgotten. Everyday words give the descriptive vocabulary of mathematics. Describing and talking about quantities and numbers is a part of mathematics after arithmetic.
More examples follow.
2.1 Airplanes or Jets We can speak about the height of an airplane above the ground. We can speak about it without measuring it and without knowing it exactly. The height will be zero when the airplane is on the ground. This height increases as the plane takes off. The height will then remain almost unchanged and nearly constant when the plane has reached its maximum height or cruising altitude.