Pythagoras. Cool.

The diagonal for PQRS is:

16^2+8^2=h^2
256+64=320
Square root of 320 is 17.89 (rounded)

The diagonal for LMNO is:

8^2+8^2=h^2
64+64=128
Square root of 128 is 11.31 (rounded)

Conclusion:

The length of diagonal Sq is not twice the size of diagonal OM.

Hope this helps 🙂