2. • The term Rational Numbers refers to any number that can
be written as a fraction.
• This includes fractions that are reduced, fractions that can
be reduced, mixed numbers, improper fractions, and even
integers and whole numbers.
• An integer, like 4, can be written as a fraction by putting the
number 1 under it.
Rational NumbersRational Numbers
4 =
4
1
3. • When multiplying fractions, they do NOT need to
have a common denominator.
• To multiply two (or more) fractions, multiply across,
numerator by numerator and denominator by
denominator.
• If the answer can be simplified, then simplify it.
• Example:
• Example:
Multiplying FractionsMultiplying Fractions
2
5
⋅
9
2
=
2 ⋅ 9
5 ⋅ 2
=
18
10
3
4
⋅
5
2
=
3⋅ 5
4 ⋅2
=
15
8
÷2
÷2
=
9
5
4. • When multiplying fractions, we can simplify the
fractions and also simplify diagonally. This isn’t
necessary, but it can make the numbers smaller and
keep you from simplifying at the end.
• From the last slide:
• An alternative:
Simplifying DiagonallySimplifying Diagonally
2
5
⋅
9
2
=
2 ⋅ 9
5 ⋅ 2
=
18
10
÷2
÷2
=
9
5
2
5
⋅
9
2
1
1
=
1⋅ 9
5 ⋅1
=
9
5
You do not have to simplify diagonally, it is just an option. If you
are more comfortable, multiply across and simplify at the end.