ABSTRACT
Preview Activity 1.1. When doing arithmetic, we often use certain properties of addition, subtrac-
tion, and multiplication to make our calculations easier or more efficient. We don’t usually state
these properties explicitly, but in order to learn more about the integers, it will be helpful for us to
do so now. As a first exercise, find the value of each of the following expressions, without using
a calculator. As you do so, explicitly identify any shortcuts you take, and state the properties that
make these shortcuts possible. Don’t worry if you don’t know or can’t remember the formal names
of the properties you use; simply describe them as precisely as you can. The first part is completed
for you as an example.
