Fractions, made simple.
A fraction describes equal parts of a whole or a collection. If a roti is cut into four equal pieces, one piece is one quarter. The pieces must be equal for this description to work. Fractions can also describe numbers greater than one, such as 5/4: one whole and one extra quarter.
Read the two numbers
In 3/4, the numerator is 3: the number of parts being counted. The denominator is 4: the number of equal parts in one whole. A denominator cannot be zero.
Find equivalent fractions
Multiplying or dividing the numerator and denominator by the same nonzero number keeps the value unchanged. For example, 1/2 = 2/4 = 3/6. Simplifying 6/8 by dividing both numbers by 2 gives 3/4.
Add and subtract like parts
When denominators match, add or subtract the numerators and keep the denominator: 2/7 + 3/7 = 5/7. When they differ, first rewrite the fractions using a common denominator so the parts are the same size.
Find a fraction of a quantity
To find 3/4 of 20 marbles, divide 20 by 4 to get 5, then multiply by 3 to get 15. Dividing finds one equal part; multiplying selects the required number of parts.
What is 1/3 + 1/4?
- Use 12 as a common denominator.
- Rewrite 1/3 as 4/12 and 1/4 as 3/12.
- Add the numerators: 4/12 + 3/12 = 7/12.
7/12
Take it with you: Fractions become easier when you keep track of the whole and the size of each equal part.