Download Review: Reducing Fractions Subtracting Fractions

Review:
Reducing Fractions
We reduce a fraction to lowest terms by finding an equivalent fraction in which the numerator and
denominator are as small as possible.
This means that there is no number, except 1, that can be divided evenly into both the numerator and
the denominator.
To reduce a fraction to lowest terms, divide the numerator and denominator by their Greatest
Common Factor (GCF). This is also called simplifying the fraction.
e.g.
To reduce a fraction, we are dividing by a FORM of ONE.
e.g.
20 = 1
20
Subtracting Fractions
When two fractions have a common denominator, we can simply subtract the numerators to
find the difference:
a – c = a-c
b b b
OR
5 – 1 = (5-1) or 4
6 6
6
6
When subtracting fractions with unlike denominators, change the fractions to equivalent
fractions which have common denominators.
e.g ¾ - ½ =
Eg.
2½- 1¾=
Math Model
________________
Multiplying Fractions
To multiply fractions, Rule 1: multiply the numerators together and multiply the denominators. Rule 2: When multiplying mixed numerals, change each mixed numeral to an improper fraction and multiply according to the rule. E.g. ½ x 2/5 = 1 x 2/ 2 x 5 = 2/10 Rule 3: express answers in simplest terms 2/10 = 1/5 Eg. 2 1/3 x ¾ E.g. 1 5/6 x 2 2/5 Manipulative or visual: e.g.1 This is a large field. We need one half of it for soccer. (shade one half). One quarter of the soccer area needs new seed (shade ¼ of the first shaded ½). ¼ of ½ = 1/8 of means times remember. e.g. 2/3 x 4/5 This means ________ OF _______________ Indicate in the drawing below, the fraction 4/5 Now, divide the area up into thirds, and shade 2/3 Answer for 2/3 of 4/5 = _____ Let’s try some here:
http://nlvm.usu.edu/en/nav/frames_asid_194_g_2_t_1.html?from=grade_g_2.html
To Help You Remember the Steps:
Use…..
This mnemonic to help you remember the steps to multiply fractions
My Dad Can’t Sing
I.
II.
IIl.
Mixed numerals to proper
Disguise whole numbers as fractions
Cancel, if possible, then multiply numerator x numerator
denominator x denominator
IV.
Simplify