Fractions Made Easy 179
For you just to look at a problem like this and call out the answer
will make everyone think you are a genius!
Here’s another: if you want to add ⅓ plus ⁄ you add 3 and 7 to get
10 for the numerator, then you multiply 3 and 7 to get 21 for the
denominator.(^1) + (^1) = 3 + 7 (^) = 10
3 7 3 × 7 21
Test you rself
Try these for yourself. Do them all in your head.
a)^1 / 4 +^1 / 3 =
b)^1 / 5 +^1 / 4 =
c)^1 / 3 +^1 / 5 =
d)^1 / 4 +^1 / 7 =
How did you do? The answers are:
a)^7 / 12 b)^9 / 20 c)^8 / 15 d)^11 / 28
You should have had no trouble with those.
SUBTRACTING FRACTIONS
A similar method is used for subtraction. You multiply the numerator
of the fi rst fraction by the denominator of the second fraction. You
then multiply the denominator of the fi rst fraction by the numerator
of the second, and subtract the answer. You fi nd the denominator
of the answer in the usual way; by multiplying the denominators
together.
Here’s an example:
cc18.indd Sec1:179 18 .indd Sec 1 : 179 1/9/07 8:40:36 AM 1 / 9 / 07 8 : 40 : 36 AM