ETan

Golden Member
Jan 23, 2001
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PROBLEM.

The number 11 can be represented using exactly three 9's as 11=99/9.

Amazingly, the number 20 can also be expressed using exactly three 9's and elementary arithmetic signs.

What is this expression?
 

arcain

Senior member
Oct 9, 1999
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9+9+sqrt(9) = 18+3 = 21

Doh.. thought that said 21! <slaps forehead>

hrmm.. must be time to go to sleep.
 

polotek147

Platinum Member
Dec 28, 2000
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So, you only have to use 9's, or can you use other #'s too? Don't mind me, my brained is pretty fried right now from the late night coding.
 

ETan

Golden Member
Jan 23, 2001
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guess i'm not the only that's stumped by this question. It's actually part of a "Problem of the Week" that the math dept hosts. I like the idea. Prize kinda sucks though... at the end of semester, winner gets $20. Not great, but it's fun, and rewarding if u win. Or loose.

AFAIK only 3 9's are allowed, no other numbers. I pretty much picked the whole thing apart yet still no answer.

Wish i could use 4 9's...
 

serialb

Diamond Member
Mar 20, 2000
3,107
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<<at the end of semester, winner gets $20. Not great, but it's fun, and rewarding if u win. Or loose>>

Aren't you cheating now?

serialb