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#1 2009-01-11 00:35:06

atut
Member
Registered: 2008-04-23
Posts: 30

hi

I just dont understand this question.....

Write each of the following numbers as a product of its prime factors:

78,                                     240,                                           420.





Answers: 78 = ---------

240 = -------

420 = --------

roflol:):|:(:D:o;):/:P:lol::mad:rolleyes::cool:dizzyeekrolleyesshame

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#2 2009-01-11 01:26:59

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: hi

For this question, you find a group of prime numbers that multiply to give the original number. The easiest way to do this is to find one prime number at a time:

78
2 x 39
2 x 3 x 13

2, 3 and 13 are all prime, so that is the answer.

(You could have had 3 x 26 in the middle if you'd taken out the 3 first, but no matter what order you do things in, the final answer will always be the same)


Why did the vector cross the road?
It wanted to be normal.

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#3 2009-01-11 02:34:17

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 48,429

Re: hi

240 = 2 x 120
240 = 2 x 2 x 60
240 = 2 x 2 x 2 x 30
240 = 2 x 2 x 2 x 2 x 15
240 = 2 x 2 x 2 x 2 x 3 x 5

This is how the number 240 is written as a product of prime numbers.
Try the third one yourself.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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