Transcript Adding and Subtracting Fractions

Math Message
1/6 of 30=
5/6 of 30 =
1/8 of 48 =
5/8 of 48 =
1/7 of 56 =
4/7 of 56 =
Adding Fractions
with SAME Denominators
When adding
fractions with like
denominators,
ONLY add the
numerators.
4
6

1
6
4+1=
Keep the
denominator the
same.
6
Try it!
2 3
 
6 6 6
Subtracting Fractions
with SAME Denominators
When subtracting
fractions with like
denominators,
ONLY subtract the
numerators.
4
6

1
6
4-1=
Keep the
denominator the
same.
6
Try it!
3 1
 
6 6 6
3 – 1 = ___
25 13


60 60 60
25 – 13 = ___
Brainpop
• BrainPOP | Adding and Subtracting
Fractions
You can add any fraction with
DIFFERET denominators…
Use what you know about equivalent
fractions to make the two fractions
have the same denominator.
2 1
 ?
5 10
2 1
4 1
So,    
5 10 10 10 10
2

5 10
2 1
5
  or
5 10 10 2
Uncommon Denominators
• You have to make them common
denominators by finding the LCD
• LCD - least common denominator (lowest
multiple of both numbers)
• Multiply numerator and denominator by the
same number to get same denominators
• Rewrite the fractions to match
2/3 + 2/6
2/3 * 2/2= 4/6
4/6 + 2/6= 6/6 = 1
Adding and Subtracting
Fractions
4
6

1
6
2
5

12 3
• S.L. 7.5
• Math Box 7.5
• U:\Math\iTLG Grade 4