I guess you mean 11+11, it's equal to 22

Woof.

:E......

Houston, we've got a problem. I solved the problem using another method and I got another result (I don't remember this result, I think it was 1.25 or something like this); I did this with two of my friends and they got to this result too, using the same method ><

I got to the same result. That's good!

20/20

Plus a brownie:

I did, this morning. 

HINT: The distance between two points A(x_A,y_A) and B(x_B,y_B​) is given by the formula:

\(AB=\sqrt{(x_B-x_A)^2+(y_B-y_A)^2}\)

It is the ratio between the circumference of a circle and the diameter. It is approximately equal to 3.14159265359.

Thanks heureka; your answer seems (and is) exact.

You got 20/20 plus a brownie:

To type aⁿ in the calculator, type a^n. The character ^ should be found on the 6 key on a QWERTY keyboard.

So to type in a⁴, write a^4.

\(E=m\cdot \Delta z\cdot g \\\Rightarrow \Delta z=\frac{E}{m\cdot g} \\m\cdot \Delta z\cdot g\geq 6.5 \\8.1\times 10^{-3}\cdot \Delta z\cdot 9.80665\geq 6.5 \\\Delta z\geq \frac{6.5}{8.1\times 10^{-3}\times9.80665}\approx 81.829 \text{ m}\)

I got the same result; that's perfect. 

20/20 and the brownie: