Fractions
Fraction Addition
1.) Find common denominator. You look for a common multiple of the denominators. 2.) Multiply across Num and Denom of first fraction, then sexond fraction 3.) Add with the new denominators
Which is greater? 4/13 or 1/3
1.) Set up fractions next to each other 2.) cross multiply the fractions and put each answer by the corresponding NUMERATOR (NOT denominator) 3x4=12 | 13x1=13 1/3 > 4/13
Fraction x Fraction
1.) multiple the numerators together to get the new number 2.) multiply the denominators to get the new number 3.) simplify (The denominator of the first fraction tells you how many parts to divide the second fraction into. The numerator tells you how many of those parts to keep.)
Simplify: 15+10/5+2
15+10/5+2= 25/7 = 3 4/7
Simplify: 15+10/5
15+10/5= 15/5+10/5= 3+2= 5
Change 3 3/4 to improper fraction
3 + 3/4 = 3/1 + 3/4 Make the denominator 4 3/1 x 4/4 = 12/4 Add together 12/4 + 3/4 = 15/4
What is 1/2 x 3/4?
3/8
Simplify: 5/15+10
5/15+10=5/25 =1/5
Simplify 18/60
Both 18 and 60 are divisible by 6. 6 goes into 18 3 times 6 goes into 60 10 times 3/10
1/4 + 1/3
CD/CM of 3 and 4 is 12 1x3=3. 1x4=4 4x 3 = 12. 3x4=12 3/12 + 4/12 = 7/12
5/7 - 1/3
CD/CM of 7 and 3 is 21 5x3=15. 1x7=7 7x3=21. 3x7=21 15/21 - 7/21 = 8/21
Reciprocals and Dividing Fractions?
Change the divisor into a reciprocal and multiply
How to compare fractions?
Cross multiply!
2/3 of 12?
Divide 12 by the denominator (3) = 4 Multiply by numerator (2) = 8
Splitting the denominator with expressions Ex) 5/10+15
NEVER SPLIT THE DENOMINATOR! Instead: simplify the denominator FIRST 5/10+15= 5/25 = 1/5
Reciprocals
Numbers that, when multiplied together = 1 Ex) 3/5 x 5/3 = 15/15=1 Ex) 2 / 1/2 = 2/1X1/2=1
1/2 x 6?
Really asking "what is half of 6?" 3!
Simplify Fractions
Recognize the Greatest Common Factor in the numerator and denominator and cancel out
Fraction Subtraction
Same as Addition, but end up with smaller NUMERATOR 1.) Find common denominator. You look for a common multiple of the denominators. 2.) Multiply across Num and Denom of first fraction, then sexond fraction 3.) Subtract with the new denominators
Biggest Rule for Simplifying Fractions with Expressions in Num or Dem
You MAY split in the Num, NEVER in the DEM Example of MAY: 15+10/5= 15/5+10/5= 3+2= 5