playing with numbers -co -primes -post 7

Good Morning Boys:

Hope you all understood well Common Factors & Common Multiples and you have done Question 1 to 4 in your Maths copy. Today we will discuss Question 5, 6 and 7 of Exercise 3.4 which are based on Co-primes.

What is Co-prime?

Any two given numbers are called co-prime numbers if their highest common factor is 1.

Let us take a few from Question 5:

(a)  18 & 35

Factors of:

18-> 1, 2, 3, 6, 9, 18

35-> 1, 5, 7, 35

Common Factor-> 1

Highest Common Factor = 1

Answer: Yes, 18 & 35 are co-primes.

    

( c ) 30 and 415

Factors of:

30-> 1, 2, 3, 5, 6, 10, 15, 30

415-> 1, 5, 83, 415

Common Factors-> 1 and 5

Highest Common Factor = 5

Answer: No, 30 and 415 are not co-primes.

I am sure, you can do the rest on your own.

Now, let us go to Question 6

A number is divisible by both 5 and 12.  By which other number will that number be always divisible?

Solution:

Find the factors of:

5-> 1, 5

12-> 1, 2, 3, 4, 6, 12

Common Factor = 1

[Note: Since their common factor is 1, the given two numbers are co-prime and is also divisible by their product 60]

Factors of 60: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60

Answer: The number is divisible by 60 as well.

Question 7: A number is divisible by 12.  By what other numbers will that number be divisible?

Solution:

Since, the number is divisible by 12; it is also divisible by its other factors-> 1, 2, 3, 4 and 6

Answer: 1, 2, 3, 4 and 6

Boys: As you have understood the above, do Exercise 3.4 Question 5(all parts), 6 and 7 in your Maths copy.

Good Morning & Thank You

Have a good day

If you have any doubts, let me know.