<20> + >22>

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<20> + >22>

by vivibcn » Sat Oct 20, 2012 2:27 am
Could you please help me with this one?

The symbol <n> represents the product of all the positive even integers less than or equal n. For example, <8> = 8 x 6 x 4 x 2 . What is the greatest prime factor of <20> + <22>
a. 7
b. 11
c. 13
d. 19
e. 23

Thank you!
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by GMATGuruNY » Sat Oct 20, 2012 4:46 am
vivibcn wrote:Could you please help me with this one?

The symbol <n> represents the product of all the positive even integers less than or equal n. For example, <8> = 8 x 6 x 4 x 2 . What is the greatest prime factor of <20> + <22>
a. 7
b. 11
c. 13
d. 19
e. 23

Thank you!
<22> = (the product of all of the positive even integers less than or equal to 20) * 22.
Thus:
<22> = <20> * 22.

Thus, we can factor out <20> from <20> + <22>:

<20> + <22>

= <20> (1 + 22)

= <20> * 23.

The correct answer is E.
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