Transcript Multiplying and Dividing Integers

Objective 3
Multiplying and Dividing Integers
© 2000 by R. Villar
All Rights Reserved
Multiplying /Dividing Integers
Ex. –3 + (–3) + (–3) + (–3)
= –12
This is the same as 4 • (–3) = –12
You can see that a positive times a negative
integer gives a negative product.
+ • – = –
– • + = –
– • – = +
+ • + = +
Ex. a. 5(–11)
– 55
What about 5(–11)(2) ?
=
–55 • 2 = –110
Rule for multiplication:
An odd amount of negatives gives a negative
product.
An even amount of negatives gives a positive
product.
Division of Real Numbers
The product of a number and its reciprocal is 1.
Here are some examples of reciprocals:
1/4 and 4
–5/2 and –2/5
–9 and –1/9
To divide a number, you can multiply by its
reciprocal. b ÷ a = b • 1/a
So the rules for dividing real numbers are the
same as multiplying real numbers.
+
–
–
+
÷
÷
÷
÷
–
+
–
+
= –
= –
= +
= +
Example: –24 ÷ (–3)
negative ÷ negative = positive
8
Example: 28
–4
–7