1. Lesson 1-3: Mult/Div Real #s
The first slides here review adding, subtracting, multiplying, and dividing fractions. You do not have to take notes on these slides. We will do a few practice problems in class.

2. Add & Subtract Fractions
Find the common denominator.
Make equivalent fractions using the new common denominator.
Add/sub the numerators. Denominator stays the same.
Simplify/reduce.
Leave improper fractions as is. Hooray!

3. Examples 1

4. 2

5. Multiply Fractions & Mixed #s
Change any mixed #s into improper fractions.
Multiply numerators.
Multiply denominators.
Simplify. (You can also simplify before you multiply.)
Leave improper fractions as is.

6. Examples 1 2 2 1

7. Divide Fractions & Mixed #s
Change any mixed #s into improper fractions.
Find the reciprocal of the 2nd fraction (the divisor), rewriting the problem as a multiplication problem.
Multiply.
Simplify. (You can also simplify before you multiply.)
Leave improper fractions as is.

8. Examples 1 2 8 5

9. Decimal Operations - Reminders
Multiplication
Line up digits as in whole # mult.
After multiplying as usual, count up total places behind decimal point, and move decimal that number of places.

10. Decimal Operations - Reminders
Division:
Shift decimal in the divisor (outside #) to the right so that you are dividing by a whole #. Shift the decimal in the dividend the same # of places. Now divide as usual.
Keep dividing until it ends or repeats.

11. Now in your Know It Notes:
Reciprocal: numerator and denominator change place (fraction flipped over)
Multiplicative inverse: a number and its reciprocal are called multiplicative inverses
A number times its reciprocal = 1

12. Inverse Prop. Of Multiplication
The product of a real # (but not zero) and its reciprocal is 1.
Algebraically: For a≠0,

13. Integer Rules Positive # • Positive # = Positive #
Negative # • Negative # = Positive #
(Same signs = positive answer)
Positive # • Negative # = Negative #
Negative # • Positive # = Negative #
(Opposite signs = neg answer)
Same rules for division.

14. Important Stuff about Zero
Zero times a number = zero
Zero divided by a number = zero
A number divided by zero = undefined
How could you make zero groups of something? It is not possible, so we get “undefined” instead.