Key Concepts and Ideas For
Fractions
Fill in the blanks for the following.
Then come up with an example that illustrates each. Hold the mouse
over the yellow box to check your answer.
- The
top number of a fraction is called the
.
- The
bottom number of a fraction is called the
.
- The
prime numbers below twenty are 2, 3, 5,
.
- To
reduce a fraction we can cancel out
.
- To
change a mixed number to an improper fraction, multiply the
by the
and add it to the
.
- When
multiplying proper or improper fractions, first
and then
.
- When
multiplying a whole number by a fraction, first change the whole number
to
and then multiply
across.
- To
divide proper or improper fractions, change to a multiplication by
multiplying by the
.
- When
multiplying or dividing mixed numbers, you must first change the mixed
numbers to
before multiplying across.
- We
find the least common denominator (LCD) of two or more fractions by finding
the least common multiple of the
.
- To
find the least common multiple, first write each of the numbers as a product
of
and then use each
prime the
number of times it
appears in any denominator.
- To
build two fractions, first find the
, and then find how
many times the
must be multiplied
to get the LCD. Finally
multiply the
by this number.
- To
add fractions with the same denominators, you get the sum’s numerators
by
the two numerators,
while the sum’s denominator is
.
- To
add or subtract proper or improper fractions with different denominators,
first find the
, then
up the fractions,
and finally add the two fractions.
- To
add mixed numbers, separately add the
parts and the
parts.
If the sum of the fractional parts produces an improper fraction,
change the improper fraction to a
number.
Then add the 1 to the whole number sum.
- To
subtract mixed numbers, separately subtract the
parts and the
parts.
Then build the fractions. If
the first fraction is smaller than the second, then
1 from the whole
number. Write this 1 as
over
. Finally add and
subtract the fractions.
- The
order of operations is
,
,
and
then
and
. If there is a tie,
then read
to
.
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