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Using specific numbers to achieve a certain number

Expert replies
by yash188 » Sat Dec 12, 2015 11:03 am
Hi,

This might be a really dumb question or maybe not but i am really stuck on this.
I am trying to achieve the number 13 using the numbers 3,5,6,7.
I have all the numbers starting from 1 to 20 except 13.
We can use any arithmetic operation to achieve the desired result.
Could someone help me with this?
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Source: — Problem Solving |

by Brent@GMATPrepNow » Sat Dec 12, 2015 11:14 am
yash188 wrote:Hi,

This might be a really dumb question or maybe not but i am really stuck on this.
I am trying to achieve the number 13 using the numbers 3,5,6,7.
I have all the numbers starting from 1 to 20 except 13.
We can use any arithmetic operation to achieve the desired result.
Could someone help me with this?
This isn't a GMAT-style question (what are the 5 answer choices?), plus it's unclear what you're trying to accomplish. Does one have to use all four numbers?

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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by yash188 » Sat Dec 12, 2015 11:18 am
Yeah I know its not a GMAT style question, but i really suck at mathematics and wanted to develop some sort of number sense before delving into the actual questions.
I found this on a Magoosh blog and wanted to try it out. The aim is to achieve numbers from 1-20 using any random 4 single digit numbers which can only be used once.

For example, to get 4 using the numbers 3,5,6,7 the following operation can be done:
7-3/6-5 = 4.

There are no options and yes we have to use all 4 numbers.
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by Brent@GMATPrepNow » Sat Dec 12, 2015 11:36 am
How about (73 + 5)/6 = 13
Brent Hanneson - Creator of GMATPrepNow.com
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by yash188 » Sat Dec 12, 2015 11:43 am
I am not sure if we are allowed to bunch numbers together or not. But I am good with it because i am pretty sure i have tried everything else :D

Thanks a lot Brent!!
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by Brent@GMATPrepNow » Sat Dec 12, 2015 11:45 am
Yeah, I wondered if that was against the "rules" as well.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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by yash188 » Sat Dec 12, 2015 11:48 am
Yeah me too since all the other 19 numbers were achieved using only arithmetic operations. And i was able to get all the 20 numbers for many other random sets of 4 single digit numbers.

But thank you for the help. I only asked when i was unable to figure this out for hours.
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