Download Adding/Subtracting Fractions

Adding/Subtracting Fractions:
1. Write the problem vertically (top & bottom)
2. Find common denominators by using the LCM “lowest
common multiple” or by multiplying the two denominators
together.
3. Change the numerator by multiplying by the same “scale
factor” you used to change the denominator.
4. Add or subtract the numerators ONLY. DENOMINATOR
STAYS THE SAME!
5. Reduce/simplify; change any improper fractions to proper
fractions by dividing the numerator by the denominator.
Additional Subtraction Rules: Borrowing
To borrow: (when the top/first fraction is less than the
bottom/second)
1. Borrow one whole number and convert to a fraction, using
the common denominator. I.e. 2/2, 5/5, 7/7….
2. Don’t forget to take away the whole number
3. Follow above directions…
 When there is no bottom/second fraction, just bring
the fraction down. It is like subtracting zero from a
number.
 When there is no top/first fraction, and there is a
bottom fraction, you need to borrow.
Multiplying Fractions
1. Write the problem horizontally (side by side).
2. Change mixed numbers to improper fractions.
(Whole number times denominator plus numerator)
3. Cross cancel if you can.
4. Multiply straight across.
5. Turn any improper fraction into a mixed number by
dividing the numerator (top #) by the denominator
(bottom #).
6. Simplify.
Dividing Fractions:
1. Write the problem horizontally (side by side).
2. Change mixed numbers to improper fractions.
(Whole number times denominator plus numerator)
3. Change the problem to multiplication by inverting
(flipping) the 2nd fraction ONLY.
4. Cross cancel if you can.
5. Multiply straight across.
6. Turn any improper fraction into a mixed number by
dividing the numerator (top #) by the denominator
(bottom #).
7. Simplify.