Identify rational and irrational numbers
Key Notes :
1️⃣ What are Numbers?
Numbers are symbols we use to count, measure, and label things.
They can be classified into Rational and Irrational numbers.
2️⃣ Rational Numbers (✅)
A rational number is any number that can be written as a fraction p/q, where:
- p = integer
- q = non-zero integer (q ≠ 0)
🟢 Examples of Rational Numbers:
- Fractions: 1/2, -3/4
- Whole numbers: 5, 0, -7
- Decimals that terminate or repeat: 0.75, 0.333…
📝 Key Points:
- ✅ Can be written as fractions
- ✅ Decimal form terminates (stops) or repeats
- ✅ Can be positive or negative
3️⃣ Irrational Numbers (❌)
An irrational number cannot be written as a fraction.
Its decimal form never ends and never repeats.
🔴 Examples of Irrational Numbers:
- √2, √3, √5
- π (Pi ≈ 3.14159…)
- e (Euler’s number ≈ 2.718…)
📝 Key Points:
- ❌ Cannot be written as a fraction
- ❌ Decimal form goes on forever
- ❌ Non-repeating decimals
4️⃣ Quick Tips to Identify ✅ vs ❌
| Clue | Rational | Irrational |
|---|---|---|
| Fraction form exists? | ✅ Yes | ❌ No |
| Decimal form? | ✅ Terminates/Repeats | ❌ Non-terminating/non-repeating |
| Examples | 2, -3, 1/4, 0.666… | √2, π, √3 |
5️⃣ Fun Emojis Trick to Remember
- ✅ Rational = “R for Regular” → neat fractions, repeats nicely ✨
- ❌ Irrational = “I for Infinite” → decimals never end 🌌
Learn with an example
➡️ Is -1 1/3 an irrational number?
- yes
- no
-1 1/3 can be written as -4/3 ,which is a fraction. So, -1 1/3
is not an irrational number.
➡️ is 5/6 a rational number?
- yes
- no
5/6 is a fraction. So, 5/6 is a rational number.
➡️ is -1 2/3 a rational number?
- yes
- no
-1 2/3 can be written as -5/3 , which is a fraction. So, -1 2/3 is a rational number.
Let’s practice!🖊️

