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.)
Since 16=2x2x2x2, I will take 3^5 and 7^2 times 11.
3x3x3x3x3x11=2673
7x7x11=539
I still need another factor hence I will take 3^4 multiply by 11.
3x3x3x3x11=891
hence, the three factors are 2673, 539 and 891.
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.
The three common factors are 3,7 and 13.
Zhiqi
ReplyDeleteTextbook p9 #25:
Your answers are right.
Did you discover there's a systematic way of getting all the factors out? :P
Textbook p9 #26:
Could you share (the thinking behind) how you arrive at these 3 numbers?
Cheers!