The silver ratio is, much like the more popular golden ratio a
mathematical concept for proportions in geometrical figures.

The silver ratio of a rectangle is as follows: the ratio of the
smaller side to the longer side equals the ratio of *half*
the longer side to the smaller side.

___________
| | ↑
| |
| |
|_ _ _ _ _ _| B
| |
| |
| |
|___________| ↓
← A →
A 0.5 B
- = -----
B A
A^{2} = 0.5 B^{2}
A 1
- = -- = 0.7071...
B √2

The silver ratio is found in ISO paper sizes. For
instance, the dimensions of an A4 sheet of paper are 21.022 by 29.730
cm; a ratio of 0.7071.