SOLUTION: write all factors: 165, 129, and 98

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Question 118433This question is from textbook Pre-Algebra
: write all factors: 165, 129, and 98 This question is from textbook Pre-Algebra

Found 2 solutions by stanbon, jim_thompson5910:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
write all factors:
165 = 3*55= 3*5*11
129 = 3*43
98 = 2*49 = 2*7^2
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Cheers,
Stan H.

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
I'll do the first one to show you how to get started:




Let's find all the factors of 165:



First take the square root of 165 to get sqrt%28165%29=12.85. Now round 12.85 to get 13. This is the number we will stop at.

So let's ask ourselves...
Is 1 a factor of 165? Since 165%2F1=165 results in a whole number, this means 1 and 165 are factors of 165.


Is 2 a factor of 165? Since 165%2F2=82.5 does not result in a whole number, this means 2 is not a factor of 165.


Is 3 a factor of 165? Since 165%2F3=55 results in a whole number, this means 3 and 55 are factors of 165.


Is 4 a factor of 165? Since 165%2F4=41.25 does not result in a whole number, this means 4 is not a factor of 165.


Is 5 a factor of 165? Since 165%2F5=33 results in a whole number, this means 5 and 33 are factors of 165.


Is 6 a factor of 165? Since 165%2F6=27.5 does not result in a whole number, this means 6 is not a factor of 165.


Is 7 a factor of 165? Since 165%2F7=23.5714285714286 does not result in a whole number, this means 7 is not a factor of 165.


Is 8 a factor of 165? Since 165%2F8=20.625 does not result in a whole number, this means 8 is not a factor of 165.


Is 9 a factor of 165? Since 165%2F9=18.3333333333333 does not result in a whole number, this means 9 is not a factor of 165.


Is 10 a factor of 165? Since 165%2F10=16.5 does not result in a whole number, this means 10 is not a factor of 165.


Is 11 a factor of 165? Since 165%2F11=15 results in a whole number, this means 11 and 15 are factors of 165.


Is 12 a factor of 165? Since 165%2F12=13.75 does not result in a whole number, this means 12 is not a factor of 165.




Remember, stop at 13. Notice how the next factor is 15 and it's already paired with 11 (ie 15%2A11=165). So this shows that any factor greater than 13 will be paired with it's corresponding factor that is less than 13. This means we only need to test numbers that are less than 13. Essentially this cuts our work in half.



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Answer:
So the factors of 165 are

1, 3, 5, 11, 15, 33, 55, and 165