Adding and Subtracting Quick and Dirty Fractions Method! Adult Numeracy N2/L2.4: Use fractions to add, subtract, multiply and divide amounts or quantities Functional Mathematics Level 2: Add and subtract fractions - add and subtract using halves, thirds, quarters, fifths and tenths
Kindly contributed to www.skillsworkshop.org by Keith Burnett, Sutton Coldfield College. ping.keith@googlemail.com To see more of Keith’s resources, including a traditional approach to adding and subtracting fractions visit http://www.slideshare.net/keithpeter
You can add two fractions by doing three multiplications and an addition!
3 2 + 5 3
3 2 + 5 3
3 2 + 5 3
3 2 + 5 3
3 2 + 5 3
3×3
3 2 + 5 3
9
3 2 + 5 3
9
3 2 + 5 3
9
5×2
3 2 + 5 3
9
10
3 2 + 5 3
9
10
3 2 + 5 3
9
10
3 2 + 5 3 5×3
9
10
3 2 + 5 3 15
9
+ 10
3 2 + 5 3 15
9
+ 10
3 2 19 + = 5 3 15 15
3 2 4 + =1 5 3 15
An example that has denominators with a common factor‌
5 4 + 6 9
5 4 + 6 9
5×9
5 4 + 6 9
45
5 4 + 6 9
45
5 4 + 6 9
45
24
5 4 + 6 9
45
24
5 4 + 6 9
45
24
5 4 + 6 54 9
45
+ 24
5 4 + 6 54 9
45
+ 24
5 4 69 + = 6 54 9 54
5 4 69 + = 6 9 54
5 4 15 + =1 6 9 54
5
5 4 15 + =1 6 9 54
5
5 4 15 + =1 6 9 54 18
5 4 5 + =1 6 9 18
You had to cancel down at the end because of the common factor‌
Mixed numbers?
Mixed numbers? Just convert to improper fractions and carry on‌
Subtraction?
Subtraction? Just subtract the top totals instead of adding‌
Your turn‌
4 7 + 5 2 Answer on next slide‌
4 7 3 + =4 5 2 10
Make up some more questions and check them with your calculator