3. ADDING RATIONAL NUMBERS WITH COMMON
DENOMINATORS
To add rational numbers that have a common
denominator, we add the numerators, but we do not
add the denominators.
4. ADDING RATIONAL NUMBERS WITH DIFFERENT
DENOMINATORS
To add rational numbers with different
denominators, first we equalize the denominators
by enlarging each rational number by the lowest
common denominator (LCD). Then we add the
numerators.
5. SUBTRACTING RATIONAL NUMBERS WITH
COMMON DENOMINATORS
Subtraction is the inverse operation of addition. To
subtract rational numbers that have a common
denominator, we subtract the numerator, but we do not
subtract the denominators.
6. SUBTRACTING RATIONAL NUMBERS WITH
DIFFERENT DENOMINATORS
To subtract rational numbers with different denominators,
first equalize the denominators and then subtract the
numerators.
7. MULTIPLYING RATIONAL NUMBERS
Multiplying Two Rational Numbers
To multiply two rational numbers, we multiply the
numerators to get the new numerator and multiply
the denominators to get the new denominator
For example:
8. Multiplying a Rational Number by a Whole
Number
To find the product of a whole number and a
rational number, first write the whole number as an
improper fraction, and then multiply. This is the
same as multiplying the numerator of the fraction by
whole number .
9. Multiplying Mixed Numbers
When we multiply two mixed numbers, first we
express each mixed number as an improper
fraction, then we find the product.
