Something Similar To Fibonacci Squares

Geometry Level 1

1 2 + 1 2 + 1 2 + 3 2 + 4 2 + 7 2 + 1 1 2 = ? 1^2 + 1^2 + 1^2 + 3^2 + 4^2 + 7^2 + 11^2 = \, ?

196 197 198 199

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6 solutions

Ashish Menon
Mar 25, 2016

Find the area of the square given in the diagram.
Its length is 11 + 7 = 18 11+7 = 18 units and breadth is 7 + 4 = 11 7+4=11 units.
So, the answer is length × breadth = 18 × 11 = 198 \text{length} × \text{breadth} = 18×11 = 198 sq.units.


Alternatively,

Addition = ( 1 + 1 + 1 + 9 + 16 + 49 + 121 = 198 ) (1+1+1+9+16+49+121 = 198)

Chung Kevin
Aug 4, 2016

If you look at the squares from the top left, you will notice that we have
3 1X1 squares,
1 3X3 square,
1 4X4 square,
1 7X7 square,
1 11X11 square.

Hence, the area of the rectangle is 1 2 + 1 2 + 1 2 + 3 2 + 4 2 + 7 2 + 1 1 2 1^2 + 1^2 + 1^2 + 3^2 + 4^2 + 7^2 + 11^2 .

We can also calculate the area of the rectangle directly. Since it has a height of 11, and a width of 18, hence it has an area of 11 × 18 = 198 11 \times 18 = 198 .

Thus, the area of the rectangle is 1 2 + 1 2 + 1 2 + 3 2 + 4 2 + 7 2 + 1 1 2 = 198 1^2 + 1^2 + 1^2 + 3^2 + 4^2 + 7^2 + 11^2 = 198 .

Unfortunately the final 11 squared was missing on my display, so I could not be certain what I was solving for.

Bill Clark - 4 years, 7 months ago

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Can you send me a screenshot of what you saw? There should be a scrol bar to indicate that the Latex equation is incomplete.

You can email me: Calvin at Brilliant.org

Calvin Lin Staff - 4 years, 7 months ago

And as an added easy way to multiply by 11. Take sum of first and second digit and place it in between the digits. 18x11 is 1(1+8)8 = 198.

David Etter - 4 years, 6 months ago

Brilliant! But try 57. Does weird stuff. 5(5+7)7 is... [5(1],2)7...(brackets mine cuz they become the 6 in 627?). So is that a repeatable pattern if the two added numbers in parentheses equal double digits? Far left ones get added? (Like the two in my brackets?) 6(6+7)7 or [6(1]3)7or 737...huh... neato.

Mama Trish - 5 months, 3 weeks ago

1 2 + 1 2 + 1 2 + 3 2 + 4 2 + 7 2 + 1 1 2 = 1 + 1 + 1 + 9 + 16 + 49 + 121 = 1^2+1^2+1^2+3^2+4^2+7^2+11^2=1+1+1+9+16+49+121= 198 \boxed{198}

Vincent Nguyen
Jan 18, 2018

You can see that the rectangle formed by the square with a side length of 11. 198 is the only number that is a multiple of 11. You can do the same for the 18, which has a factor of 3. 198 is the only multiple of 3 ( 1 + 9 + 8 = 18 (1+9+8=18 1 + 8 = 9 ) 1+8=9) .

Laura Gao
Feb 25, 2018

the hard way: count the squares

the easy way: 11 18 11*18 do the math

Mxjd Ultimate
Jun 5, 2021

Find out the area, which is 11 x 18

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