Three 8's make 6

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8 8 8 = 6

Any mathematical operation can be used except the ones involving writing a number or a letter.

(eg. you cannot use cube root or square as it involves writing a number 1/3 or 2 respectively ).

Hint : You can use square root as it doesn't involve writing a number.

Yes No

1 solution

Yeshas Bharadwaj
Dec 29, 2015

Well there may be different answers but mine is $(\sqrt { ((8-8)!+8) })!$

Using square root is not permitted.

Rishabh Jain - 5 years, 5 months ago

yes it doesn't involve writing a number

Yeshas Bharadwaj - 5 years, 5 months ago

Square root of a number n can be considered as n^(1/2), so it does involve writing a number.

Roberto Gallotta - 5 years, 5 months ago

@Roberto Gallotta – but you can also write it the way I have written so it is valid

Yeshas Bharadwaj - 5 years, 5 months ago

@Yeshas Bharadwaj – I'm having a slightly hard time telling if you're serious or not. From your problem: "(eg. you cannot use cube root or square as it involves writing a number 1/3 or 2 respectively ). Hint : You can use square root as it doesn't involve writing a number." You're bending the rules just to be right. Square root can be expressed as exponential (x^1/2) the same way cube root can (x^1/3). The fact that when you write the square root no number appears is because the "2" of square root is implied.

Roberto Gallotta - 5 years, 5 months ago

I think 8!!/(8x8)=6 is a solution. 8!! = (2^4)x4! = 384 384/64 = 6. I just wish I'd thought of that sooner...

Roberto Gallotta - 5 years, 5 months ago

Dude 8!! is infinity as it doesn't mean 8!*8! anyway that wouldn't give you 6

Yeshas Bharadwaj - 5 years, 5 months ago

First off, I know 8!! is not 8!x8!, that's why I specified "8!! = (2^4)x4! = 384" in my solution. Secondly, 8!! is not infinity since, for even numbers (such as 8), the double factorial n!! is equal to 2^k x k!, where 2k=n. And finally, yes, it does give you 6. Just do the operations yourself if you don't believe me :)

Roberto Gallotta - 5 years, 5 months ago

Three 8's make 6

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