Fun math problem that stumps everyone

[Out-to-Lunch]

(2+i)*(2-i) ?

Here, of course, i=sqrt(-1)

 

[ERD50]

BZZZZZT! Try again! (edit, I see you caught this before I posted)

* two, and only two, 2s, and

Spoiler (scroll down for answer)















(2^2) + (2/2) = 5

 

[ERD50]

(2+i)*(2-i) ?

Here, of course, i=sqrt(-1)

Isn't adding another number/variable/constant a violation?

How about:

Round to zero the Square root of 22. (I have to check how to use the basic math symbols for "round", vs computer/spreadsheet nomenclature...

But in my computer calculator:



round(sqrt(22)) = 5


-ERD50

 

[Out-to-Lunch]

Isn't adding another number/variable/constant a violation?

Yeah, I concede that i could be considered a number, violating the premise. But, I thought of that solution, so I figgered I would throw it out there anyway!

I wondered philosophically about what constitutes an "operation" vs. a "number." For example, I was thinking about ln(), which seems clearly to be an operation, but for its inverse, exp(), you could squawk about its using a number, 2.182818...

 

[ERD50]

Yeah, I concede that i could be considered a number, violating the premise. But, I thought of that solution, so I figgered I would throw it out there anyway!

I wondered philosophically about what constitutes an "operation" vs. a "number." For example, I was thinking about ln(), which seems clearly to be an operation, but for its inverse, exp(), you could squawk about its using a number, 2.182818...

Right, in a similar vein, is the Square Root function not using a number? It can also be expressed as X ^ .5. But I think my solution fits the premise of the challenge:

round(sqrt(22)) = 5


And the use of "22" versus "two 2's" is a nice fit to a puzzle, a little out-of-the-box thinking? I admit I looked at quite a few operations involving "two 2's" before considering "22".


-ERD50

 

[f35phixer]

here is the one answer, and they said there are more possible...

The square root of point 2 to the power of minus 2.

sqrt ( (.2)^(-2) )

.2^(-2) is the same as 1/0.04, i.e. 25

[Point 2 is usually written as 0.2, but .2 is also correct.]

 

[Out-to-Lunch]

here is the one answer, and they said there are more possible...

The square root of point 2 to the power of minus 2.

sqrt ( (.2)^(-2) )

.2^(-2) is the same as 1/0.04, i.e. 25

[Point 2 is usually written as 0.2, but .2 is also correct.]

Very clever!

 

[f35phixer]

Very clever!

For someone, I'm not that smart Lunch ;-)

 

[Out-to-Lunch]

For someone, I'm not that smart Lunch ;-)

Ha ha!

I maintain that my #175 solution met the letter of your challenge, but concede that it did not meet the spirit of it. Yours is elegant.

 

[Jerry1]

here is the one answer, and they said there are more possible...

The square root of point 2 to the power of minus 2.

sqrt ( (.2)^(-2) )

.2^(-2) is the same as 1/0.04, i.e. 25

[Point 2 is usually written as 0.2, but .2 is also correct.]

I thought the answer had to equal “exactly 5”. How does 25 satisfy that?

 

[ERD50]

I thought the answer had to equal “exactly 5”. How does 25 satisfy that?

He was just breaking it down. Take that 25, then apply the included "sqrt" function, which is exactly 5.

-ERD50