rules for fractions addition, subtraction, multiplication and division
TRANSCRIPT
Rulesfor
Fractions
Addition, Subtraction,
Multiplication and Division
Fractions
Numerator --------- 3
---
Denominator -------- 5
Reminders:
1) “D” is down 2) N.o.D Numerator over Denominator
Equivalent
Reducing Reverse
8
---
10
(÷ 2)
(÷ 2)
4
= ---
5
4
---
5
* (5)
* (5)
20
= ---
25
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|
|
|
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Addition/Subtraction
Convert fractions to have common denominators, – Use LCM or– Multiply the Denominators together
Add or Subtract the numerators
Addition Example
or as a Mixed number: 1 and 1/14
4 1
--- + ---
7 2
8 7
= --- + ---
14 14
15
= ---
14
Multiplication
A) Reduce Last– Multiply the Numerators– Multiply the Denominators– Reduce
B) Reduce First– Reduce– Multiply the Denominators– Multiply the Numerators
Multiplication ExampleReduce Last
7 3
Problem: --- * --- =
8 14
NOTE: The hard part is finding the GCF
A) 21
---
112
(÷ 7)
(÷ 7)
3
= ---
16
Multiplication ExampleReduce First
7 3
Problem: --- * --- = 8 14
B) 1
--- * ---
2
3
= ---
16
/ ÷ 7
/ ÷ 7
B) 3
--- * ---
8
Division
Flip the second fraction Change division to multiplication Then multiply
12
---
14
7
* ---
3
1
= --- * ---
2
2
= ---
1
3
÷ ---
7*
/ ÷ 7
/ ÷ 7
/ ÷ 3
/ ÷ 3
4
= --- * ---
1
/ ÷ 2
/ ÷ 2
= 2
2
1
Summary
Addition/Subtraction – – Must have common denominators, then– Add the Numerators
Multiplication – – Multiply then reduce, or – Reduce then multiply
Division – – Flip second fraction, then – Multiply