Reducing Fractions By
Prime Factorization
You will use two skills for this:
1) Prime factorization
2) Reducing fractions to 1
Remember:
Factorization:
There are two methods. Pick what works for you.
Trees:
24
8•3
2 •4
Stacked Division:
2
2 4
3 12
2 24
2• 2
Prime Factorization: 24 = 2 • 2 • 2 • 3
Remember:
We aren’t randomly crossing o numbers. We are identifying the
same number each time it occurs in the numerator and
denominator. For example: remember that 2÷2=1, and that 1
times any number is that number. Because we know this in our
minds, we do not write the 1.
ff
2•2•3•5
2
2
﹦
﹦
3•5
15
2•3•3•5•5
72
Reduce
100
2
2
3
2
72
100
﹦
3
6
12
36
72
2•2•2•3•3
2•2•5•5
5
2 10
5 50
2 100
2•3•3
5•5
﹦
﹦
18
25
75
Practice:
180
5
3 15
5 75
75
180
﹦
3•5•5
2•2•3•3•5
3
5
2
2
3
9
45
90
180
﹦
5
2•2•3
﹦
5
12
63
Practice:
140
3
3 9
7 63
63
140
﹦
2
5 10
2 20
7 140
3•3•7
2•2•5•7•5
3•3
2•2•5•5
﹦
﹦
9
100
45
Practice:
132
2
2 4
3 12
5 60
60
132
2
3 6
2 12
11 132
2•2•3•5
2 • 2 • 3 • 11
﹦
5
﹦ 11