Calculating with fractions
Add, subtract and find fractions of amounts.
Sharing food
Cooks share food into halves, quarters and eighths. We can find a fraction of a number by dividing. And we can add and take away fractions.
Fractions of amounts
To find ¼ of 24, divide by 4: 6. To find ¾ of 24, find ¼ and multiply by 3: 18. A fraction is a division: 3/4 means 3 ÷ 4.
Simplifying
4/8 and ½ cover the same amount. To simplify, divide the top and bottom by the same number: 4/8 = ½. Simple fractions are easier to compare.
Adding and taking away
With the same denominator, add the tops: 3/4 + 2/4 = 5/4. 5/4 is an improper fraction – more than one whole: 1¼. Taking away works the same: 5/4 − 2/4 = 3/4.
Halves and quarters together
Halves and quarters are related: ½ = 2/4. So ½ + ¼ = 2/4 + 1/4 = 3/4. Estimate first: ½ + ¼ is less than 1.
What I learnt
- I can find fractions of amounts.
- I can simplify fractions.
- I can add and subtract fractions with the same or related denominators.