Adding fractions with Unlike denomintors
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To add fractions, you must first find the least common denominator (LCD) and rewrite the fractions with that denominator. Then, add the numerators and put the sum over the common denominator. For example, to add 6/7 + 1/2: 1) The LCD is 14 2) Rewrite as 12/14 + 7/14 3) Add the numerators: 12 + 7 = 19 4) Write the sum over the LCD: 19/14 5) Simplify the resulting improper fraction to get the final answer of 1 5/14.
Adding fractions with Unlike denomintors
- 2. Review • Lets begin by review the parts of a fraction- –The Numerator is the number on top. –5 6 –The Denominator is the number on the bottom. –5 6
- 3. Rules for adding…. • This is the single most important thing to remember!!! • Ex: ½ + ¾ = this does not add up! • If the denominators are not the same you can not add or subtract them. • Ex: 3/5 + 1/5 = 4/5
- 4. Steps for Adding • Find the Least Common Denominator (LCD) of the fractions, the prime numbers chart will help determine the LCD. • Rename the fractions to have the LCD • Add the numerators of the fractions • Simplify the Fraction • * Now lets do one together.
- 5. Step 1 Find the LCD • 6/7 + ½=? • The LCD would 14, that is the lowest number 7 and 2 divide into equally. • 14/2=7 • 14/7=2
- 6. Review • Prime numbers-is any number that can be divided, without a remainder, only by itself and by 1. • Ex: 11 can only be divided by itself or 1.
- 7. Step 2 Make equivalent fractions • Since 7 goes into 14 two times we multiply the numerator by 2. • Hence 6/7 now equals 12/14. • The denominator 2 divides 14 by 7, so we multiply the numerator by 7, now ½ = 7/14
- 8. Step 3 Add the Numerators • 12/14 +7/14= • 12+7= 19 • 19/14
- 9. Step 4 Simplify 19/14 We now have an improper fraction. 14 divides into 19 one time. There will be a remainder of 5. 1 5/14 is our answer.