Compare rational numbers
Key notes:
🔢 What are Rational Numbers?
- A rational number is any number that can be written as a fraction:
👉 a/b, where a and b are integers and b ≠ 0 - Examples: 1/2, -3/4, 5, 0, -7/1
📏 Convert to Same Form Before Comparing
To compare rational numbers, convert them into:
✔️ Fractions
✔️ Decimals
✔️ Like denominators
Example:
Compare 2/3 and 3/5 → Make denominators same or convert to decimals.
🟰 Use Common Denominators
🌟 Rule: When denominators are the same,
➡️ The number with the bigger numerator is greater.
Example:
- 7/12 > 5/12 👍
💡 Use Number Line
- Numbers on the right 👉 are greater than numbers on the left 👈.
- Example:
- −2 is to the right of −5, so −2 > −5 😊
🔍 Compare Using Decimals
Convert both numbers into decimals for easy comparison.
Example:
- 1/4 = 0.25
- 2/5 = 0.40
So, 2/5 > 1/4 ✔️
➕➖ Be Careful with Negative Rational Numbers
💥 Rule:
- The rational number closer to zero is greater when negative.
Example: - −1/3 > −1/2
Because −1/3 is closer to 0.
🔢 Cross Multiplication Method
Use when denominators are different:
Compare a/b and c/d
👉 Cross multiply: a × d and b × c
- If a × d > b × c, then a/b > c/d
Example:
Compare: 3/4 and 5/8
- 3 × 8 = 24
- 4 × 5 = 20
➡️ 24 > 20 so 3/4 > 5/8 🎉
🎯 Remember the Order
👉 Smallest → Largest
👉 Negative < Zero < Positive
Example order:
- −3/2, −1/4, 0, 2/3, 5/4
🌈 Summary Chart
| Method | When to Use | Emoji |
|---|---|---|
| Common denominator | Comparing fractions | ➗ |
| Number line | Visual comparison | 📉 |
| Decimals | Easy comparison | 🔢 |
| Cross multiplication | Fast for unlike denominators | ✖️ |
Learn with an example
⛳ Which sign makes the statement true?
-8 ____ -1/2
- Remember that when comparing negative numbers, larger numbers like 8 (if you ignore the minus sign) are less than smaller numbers like 1/2.
- So: -8 < -1/2
⛳ Which sign makes the statement true?
-2 3/8 _____ 0
- A negative number like -2 3/8 is always less than zero.
- So: -2 3/8 < 0
⛳ Which sign makes the statement true?
0 ____ -5 5/8.
A negative number like -5 5/8 is always less than zero.
So: 0 > – 5 5/8
Let’s practice!🖊️

