What Are Divisibility Rules?
Divisibility rules are like math superpowers!
They help you quickly determine if one number can be divided by another without actually doing the division. These handy shortcuts will save you time and make math problems easier!
Common Divisibility Rules
Divisible by 2:
A number is divisible by 2 if its last digit is even (0, 2, 4, 6, or 8).
Example: 346 (ends with 6 → divisible by 2)
Divisible by 3:
Add all digits. If the sum is divisible by 3, so is the number.
Example: 123 (1+2+3=6 → 6 is divisible by 3 → 123 is divisible by 3)
Divisible by 5:
A number is divisible by 5 if it ends with 0 or 5.
Example: 1,250 (ends with 0 → divisible by 5)
Divisible by 9:
Add all digits. If the sum is divisible by 9, so is the number.
Example: 729 (7+2+9=18 → 18 is divisible by 9 → 729 is divisible by 9)
Let's Practice!
Example 1: Is 4,725 divisible by 9?
Try it yourself before checking the answer!
Let's add the digits: 4 + 7 + 2 + 5 = 18
18 is divisible by 9 (9 × 2 = 18), so YES, 4,725 is divisible by 9!
Great job! You're getting the hang of this!
Example 2: Which numbers between 2 and 10 divide evenly into 1,260?
Test each rule to find all the correct answers!
Let's check each number:
- 2: Ends with 0 (even) → YES
- 3: 1+2+6+0=9 → 9 is divisible by 3 → YES
- 4: Last two digits (60) ÷ 4 = 15 → YES
- 5: Ends with 0 → YES
- 6: Divisible by both 2 and 3 → YES
- 7: (Requires actual division) → YES (1260 ÷ 7 = 180)
- 8: Last three digits (260) ÷ 8 = 32.5 → NO
- 9: 1+2+6+0=9 → 9 is divisible by 9 → YES
- 10: Ends with 0 → YES
Amazing! You've mastered multiple divisibility rules!
Parent Tips 🌟
- Make it a game: Challenge your child to find divisible numbers in license plates, addresses, or phone numbers during car rides.
- Real-world connections: Show how divisibility rules help with splitting bills, sharing items equally, or checking sales discounts.
- Flashcard practice: Create flashcards with numbers on one side and which numbers they're divisible by on the back for quick practice.