In these examples, we're going to be working
with signed numbers by placing numbers on
the number line. So the first example say
that the counting numbers, 0, and the negative
counting numbers comprise what are called
integers. Let's label the number line so that
it includes 0, and the integers from -5 to
5. So I'm going to start by putting 0 here,
and then what I'm going to do is to count
1, 2, 3, 4, 5. So that's 0 and the first five
counting numbers, so let's insert the negative
of those, -4, and -5. So we have now labelled
the number line so that it includes 0, and
the integers from -5 to 5. We could also use
the number line to label fractions, and fractions
can be signed as well. In this example, we
want to include the numbers from -1 to 1,
incremented by 1/5. So I'm going to start
again with 0, and then I would have 1/5, 2/5,
3/5, 4/5, 5/5, which is also known as 1. If
I go to the left of 0, then I get -1/5, -12/5,
-3/5, -4/5, and -5/5, which is equal to -1.
