Download Multiplying Rational Numbers (2.4)

Multiplying Rational Numbers (2.4)
(Remember: Rules for rational numbers are the same as they were for integers)
Multiplying Decimals:
 When multiplying, decimals DO NOT have to line up. You multiply the
numbers as if they were whole numbers. When you are finished, count
how many numbers are behind the decimals in your problem….that’s
how many should be behind the decimal in your answer.
Examples:
3.65 x (-2.9)
-0.814 x (-5.12)
-13(2.47)
Multiplying Fraction:
 When multiplying fractions, you DO NOT have to have common
denominators! Simply line up your fractions and multiply straight
across. Remember to simplify your answers.
Examples:
3 6
x =
5 7
-1
3 4
( )=
8 5
5
6
-2 (- ) =
4
1
2
x (-3 ) =
7
9
Dividing Rational Numbers (2.4)
(Remember: Rules for rational numbers are the same as they were for integers)
Dividing Decimals:
 When dividing decimals:
o Step 1: Set up numbers using the ‘house’. (Remember: the first
number gets inside, the second number has to stay outside.)
o Step 2: Move the decimal in the number ‘outside the house’ to
the end of the number. However many times you moved it, you
do the same to the decimal on the number ‘inside the house’.
o Step 3: Divide.
Examples:
-0.72 ÷ (-0.9) =
-16.29 ÷ 3.62 =
14.616 ÷ (-2.32) =
Dividing Fraction:
 When dividing fractions, you DO NOT have to have common
denominators!
o Step 1: Make sure all numbers are written as fractions.
o Step 2: KCF (Keep it, Change it, Flip it)
o Step 3: Multiply and Simplify
Examples:
1
5
- ÷ (-
2
)=
3
2
÷ (-14) =
3
2
5
2
7
-6 ÷ (-2 ) =