Prime Factorisation
Textbook p9 #25:
The Prime factorisation of a number is 2^4 X 3^5 X 7^2 X 11.
Write down 3 factors of the number that are greater than 100.
(Hint: 16 X 11 = 176, which is a factor.)
How I work out my answer:
First, I know that 2,3,7 and 11 are factors of the number but they are smaller than 100.
As to find out 3 factors of the number that are greater than 100, I simply just take 7^2 X 11 and 3^5 X 11. Like this, I will get 539 and 2673.
Because of the example given is the answer of 2^4 X 11, I feel that i should not write the same. Therefore I simply just take 3^4 X 11 and got 891 as another answer.
Lastly, I calculated 2^4 X 3^5 X 7^2 X 11 and the answer is 2095632.
I then use the answer to divide the factors to ascertain my answer.
So, my answer is: 539, 891 & 2673.
Textbook p9 #26:
The Prime factorisation of two numbers are 2 X 3^2 X 7^3 X 13 and3 X 7^2 X 13^3 X 17 .
Write down 3 common factors of the numbers.
From these two numbers, I can see some similar prime factors in them.
So, I simply see what are the similar prime factors and they are the common factors of this two numbers.
They are: 1(a common factor is every number above 0),3 & 7.
JJ(:
posted by Chan Jing Jie at
11:14 PM
1 Comments:
Jing Jie
Textbook p9 #25:
Indeed, you have articulated your thinking clearly :D
Your answers are correct, and have made good use fo the final figure (2095632) to help check your answer.
Indeed, apart from using it to check your answer, have you considered using this final figure (2095632) to help you find the factors?
Textbook p9 #26:
Good observation :D
You are correct.
You think you could find more common factors?
Cheers!
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