Last updated at Jan. 3, 2019 by Teachoo

Transcript

Ex 3.4, 6 A number is divisible by both 5 and 12. By which other number will that number be always divisible? We know that If a number is divisible by two co-prime numbers, it is divisible their product Let’s check if 5 & 12 are co-prime Factors of 5 1 × 5 = 5 5 × 1 = 5 We stop here as 5 & 1 have occurred earlier Factors of 5 are 1, 5 Factors of 12 1 × 12 = 12 2 × 6 = 12 3 × 4 = 12 4 × 3 = 12 We stop here as 4 & 3 have occurred earlier Factors of 12 are 1, 2, 3, 4, 6, 12 Since common factor of 5 & 12 is 1 ∴ 5 & 12 are co-prime Now, If a number is divisible by two co-prime numbers, it is divisible their product Product = 5 × 12 = 60 So, if a number is divisible by 5 & 12, then number will also be divisible by its product 60

Chapter 3 Class 6 Playing with Numbers

Concept wise

- Factors and Multiples
- Perfect number
- Prime and Composite Numbers
- Sum of prime numbers
- Prime numbers from 1 to 100
- Divisibility Tests - Divisibility by 5, 10, 2
- Divisibility Tests - Divisibility by 4, 8
- Divisibility Tests - Divisibility by 3, 6, 9
- Divisibility Tests - Divisibility by 11
- Divisibility Tests - All
- Common Multiples
- Common Factors
- More Divisibility Rules
- Factor Tree
- Prime Factorisation
- Highest Common Factor
- Lowest Common Multiple
- Statement questions on LCM
- Statement questions on HCF

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.