What is a fraction?
A fraction shows part of a whole. In 3/4, the bottom number (denominator) tells how many equal parts, and the top number (numerator) tells how many we take. So 3/4 means 3 out of 4 equal parts.
Key idea / 要点
To add or subtract fractions with the same denominator, add or subtract the top numbers and keep the bottom number: a/d + b/d = (a+b)/d.
Adding fractions
Worked example / 例题
Add ½ + ¼.
Change ½ into quarters: ½ = 2/4.
2/4 + 1/4 = 3/4.
So ½ + ¼ = ¾.
Equivalent fractions
Fractions can look different but be equal. Multiply top and bottom by the same number: 1/2 = 2/4 = 4/8. This helps us give fractions the same denominator before adding. To compare fractions that share a denominator, the one with the bigger top number is larger, so 3/4 is bigger than 1/4.
Remember / 记住
- Denominator = number of equal parts (bottom).
- Same denominator → just add or subtract the tops.
- Simplify the answer when you can.