The Eleven Eleven Plus!

Logic Level 1

If it possible to arrange five square tiles numbered $1, 2, 3, 4,$ and $5$ into a "plus" so that the sum of the three-tile column and the sum of the three-tile row are both equal to $11$ , what number is in the center?

I don't know how to code!

1 4 3 It is not possible. 2 5

2 solutions

Vinayak Srivastava
May 30, 2020

The total sum of the tiles given in the grid is $11+11=\textcolor{#BA33D6}{\boxed{22}}$ .

The sum of first five natural numbers is $\dfrac{5(6)}{2}=\textcolor{magenta}{\boxed{15}}$ .

If it is possible,

number at the center $=\textcolor{#BA33D6}{\boxed{22}}-\textcolor{magenta}{\boxed{15}}=\textcolor{#D61F06}{\boxed{7}}$

Since there is no $7-$ tile, it is not possible!

Will this method work for all sorts of questions similar to this?

Vicky Clearwater - 1 year ago

Yes, the concept used is the same, but may require more thinking for more difficult questions.

Vinayak Srivastava - 1 year ago

Yes as it we are trying to find the sum of the numbers equal to 9.

Unaming Gaming - 1 year ago

Joyce Wong
May 30, 2020

The middle number is 3 because (1+2+3+4+5)/2 is 3. 11-3=8 but it takes 3 numbers (4+2+1) to make 8. There are only 2 spaces to put the numbers, therefore, it is not possible.

I don't think you can do that. after adding 1+2+3+4+5, you have to add the middle number again before dividing by two. Asuming x is the middle number, you have to subtract 11 from 3+x/2 or (15+x)/2 . Lastly (1+2+3+4+5)/2 doesn't equal 3.

BigBrain HighIQ - 11 months ago

The Eleven Eleven Plus!

2 solutions

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