📖 NOTES
Class 5
Chapter 13: Animal Jumps
Math Mela · Quick Revision Notes
Class 5Math Mela (NCERT)Chapter 13
📚 What's in this Chapter
🔢 Factors & Arrays
🔑 Factor
A factor of a number divides it completely, with no remainder. You can see factors by arranging objects into equal rows and columns (an array)!12: arrays are 1×12, 2×6, 3×4 → Factors of 12 = 1, 2, 3, 4, 6, 12
🌟 Every number has 1 and itself as factors. A prime number (like 13 or 37) has ONLY these two factors — nothing else divides it evenly!
✖️ Multiples
🔑 Multiple
A multiple of a number is what you get by multiplying it by 1, 2, 3, 4... (i.e., jumping by that number repeatedly from 0).Multiples of 4: 4, 8, 12, 16, 20, 24...
💡 Factors and multiples are opposite ideas: FACTORS divide a number; MULTIPLES are what you get by multiplying it. 3 is a FACTOR of 12; 12 is a MULTIPLE of 3.
🐰🐸 Common Multiples
🔑 Common Multiple
A number that appears in the multiples list of BOTH numbers.Rabbit jumps by 4, Frog jumps by 3 — both starting at 0:
Multiples of 4: 4,8,12,16,20,24,...
Multiples of 3: 3,6,9,12,15,18,21,24,...
Common multiples: 12, 24, 36...
Multiples of 3: 3,6,9,12,15,18,21,24,...
Common multiples: 12, 24, 36...
🌟 Special case: If one number is already a multiple of the other (like 3 and 6), then EVERY multiple of the bigger number is automatically a common multiple!
🎯 Common Factors
🔑 Common Factor
A number that divides BOTH given numbers exactly.Factors of 24: 1,2,3,4,6,8,12,24
Factors of 36: 1,2,3,4,6,9,12,18,36
Common factors: 1, 2, 3, 4, 6, 12
Factors of 36: 1,2,3,4,6,9,12,18,36
Common factors: 1, 2, 3, 4, 6, 12
🌟 1 is ALWAYS a common factor of any two numbers! And for two CONSECUTIVE numbers (like 12 and 13), the ONLY common factor is 1.
🔍 Divisibility by 2, 5, and 10
| Divisible by | Rule |
|---|---|
| 2 | Ends in 0, 2, 4, 6, or 8 (even number) |
| 5 | Ends in 0 or 5 |
| 10 | Ends in 0 (this means it's ALWAYS divisible by both 2 AND 5 too!) |
📝 Chapter Summary
- Factor = divides a number exactly; Multiple = result of multiplying
- Every number has 1 and itself as factors; primes have ONLY these two
- Common multiple = appears in both numbers' multiple lists
- Common factor = divides both numbers exactly; 1 is always one
- Two consecutive numbers always have only 1 as their common factor
- Divisible by 10 ⟺ divisible by both 2 and 5