Exercise 3.4
1. To find the common factors of multiple numbers, we list the factors of each number and identify the factors they have in common.
- For 4, 8 and 12: Factors of 4: is 1,
, 4 and Factors of 8: 1, 2, , and Factors of 12: 1, , , 4, , . - Common factors are:
, , . - For 5, 15 and 25: Factors of 5: is 1,
and Factors of 15: 1, , 5, and Factors of 25: 1, , - Common factors are:
, .
Find first three common multiples of :
(a) 6 and 8 :
Multiples of 6 : 6, 12,
Mutltipes of 8 : 8, 16, 24,
The first three common multiples are:
(b) 12 and 18 :
Multiples of 12: 12, 24,
Multiples of 18: 18, 36,
The first three common multiples are:
5.Which of the following numbers are co-prime?
6. A number is divisible by both 5 and 12. By which other number will that number be always divisible?
7. A number is divisible by 12. By what other numbers will that number be divisible?
If a number is divisible by 12, it means it is a multiple of 12. To find the other numbers by which it will be divisible, we need to find the factors of 12.
The factors of 12 are 1,
Therefore, a number that is divisible by 12 will also be divisible by 1, 2, 3, 4, 6, and 12.