adding fractions
DESCRIPTION
Adding Fractions 1. Adding Fractions with Common Denominators Add the Numerators. Keep the Denominators the same. 2. Practice time 3. Reduce or simplify if necessary… 4. Adding Fractions with Unlike Denominators 5.Find a common denominator using LCM. Multiply numerator and denominator by LCM. Add the converted fractions. 6. Least Common Multiple 7. We need to create fractions with like denominators in order to add these fractions. This is where we need LCM (Least Common Multiples) 8. The first common multiple is the Least Common Multiple This will become the new denominators in order to create like denominators to add fractions. 9. Adding Fractions with Unlike Denominators Multiples of 7: 7, 14, 21, 28 Multiples of 4: 4, 8, 12, 16, 20, 24, 28 10. Practice time Common Multiples for these numbers: 6: 5: What is the LCM? 11. Review In order to add fractions, what must you have? Explain a simplified fraction What is an LCM? What are LCMs used for? Why is it important to be able to find an LCM?TRANSCRIPT
Adding Fractions with Common Denominators
1. Add the Numerators.
2. Keep the Denominators the same.
3 5+
11 11
=8
11
3 5+
11 11=
+2
9=
9
5
9
16+
4
16=
Reduce or simplify if necessary…
2
15+
3
15=
5
15
5
15÷
5
5=
1
3
What does it mean to reduce
or simplify?
+2
9=
9
4
+3
12=
12
6
+2
15=
15
7
+1
16=
16
1
Adding Fractions with Unlike Denominators
1. Find a common denominator using LCM.
2. Multiply numerator and denominator by LCM.
3. Add the converted fractions.
What is an LCM?
+2
3
=
6
5
We need to create fractions with like denominators in order to add these fractions. This is where we need LCM (Least Common Multiples)
3: 3, 6, 9, 12, 15, 18
6: 6, 12, 18
•The first common multiple is the Least Common Multiple
• This will become the new denominators in order to create like denominators to add fractions.
•List the multiples for each of the factors (denominators)
Adding Fractions with Unlike Denominators
3
7+
3
4=
Multiples of 7:
Multiples of 4:
7, 14, 21, 28
4, 8, 12, 16, 20, 24, 28
3
7
1228
=
3
4 =
21
28
X 4
X 4
X 7
X 7
3 3
7 4 +
12 21
28 28 +
START
READY TO ADD
Common Multiples for these numbers:
6:
12: What is the LCM?
Common Multiples for these numbers:
8:
12: What is the LCM?
Common Multiples for these numbers:
9:
12: What is the LCM?
Common Multiples for these numbers:
4:
12: What is the LCM?
Common Multiples for these numbers:
3:
5: What is the LCM?
Common Multiples for these numbers:
7:
16: What is the LCM?
Common Multiples for these numbers:
6:
5: What is the LCM?
+2
3=
9
4
What is the LCM that you need for a common denominator?
+4
9=
12
5
What is the LCM that you need for a common denominator?
+4
7=
9
5
What is the LCM that you need for a common denominator?
+2
3=
6
5
What is the LCM that you need for a common denominator?
+4
9=
2
1
What is the LCM that you need for a common denominator?
REVIEW
• In order to add fractions, what must you have?
• Explain a simplified fraction
• What is an LCM?
• What are LCMs used for?
• Why is it important to be able to find an LCM?