Fraction Rules
What is a strategy to simplify fractions? What do we use?
Find the GCF.
Divide the numerator (top) and denominator (bottom) by the GCF.
2/3 * 4/5
8/ 15
1/2 * 5
1/2 x 5/1 = 5/2 = 2 1/2
What is the reciprocal of
11/8
8/11
2/3 divide 2/9
2/3 x 9/2 = 18/6 = 3
How do we change a whole number into a fraction?
Put a 1 in the denominator, or put it over 1.
3/5 * 7/8
21/40
5/6 * 3/10
15/60 = 1/4
1/8 -: 3
1/8 divide 3/1 = 1/8 x 1/3 = 1/24
14 1/2 - 5 3/4
14 2/4 - 5 3/4 = 13 6/4 - 5 3/4 = 8 3/4
3 word phrase to help us with dividing fractions.
Keep - Change - Flip
*Multiply by the the reciprocal.
4 * 7/8
4/1 x 7/8 = 28/8 = 3 4/8 = 3 1/2
1/3 * 1/4
1/12
6 -: 1/8
6/1 divide 1/8 = 6/1 x 8/1 = 48/1 = 48
3 2/3 - 1 3/4
44/12 - 21/12 = 23/12 = 1 11/12
How do we convert mixed numbers into improper fractions?
Use the C method
5/12 * 9
5/12 x 9/1 = 45/12 = 3 9/12 = 3 3/4
1/3 * 6/7
6/21 = 2/7
12 divide 2 1/3
12/1 divide 7/3 = 12/1 x 3/7 = 36/7 = 5 1/7
6 - 2 2/3
6/1 - 8/3 = 18/3 - 8/3 = 10/3 = 3 1/3
What should you do first to mixed numbers when multiplying or dividing fractions?
Convert them to improper fractions.
Change them to improper fractions.
Make them improper fractionns.
2/9 * 3/8
6/72 = 1/12
2/3 * 1/4
2/12 = 1/6
3 1/5 divide 1 1/2
16/5 divide 3/2 = 16/5 x 2/3 = 32/15 = 2 2/15
Solve:
5 3/4 divide 2 1/2 =
23/4 divide 2 1/2 = 23/4 x 2/5 = 46/20 = 2 6/20 = 2 3/10