mrs. brenda windsor 2008 adding fractions with common denominators 1.add the numerators. 2.keep the...
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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=
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?
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
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