The 1961 GCE O-level exam included this question:
If one square yard of material costs 18 pence, what is the price of one square foot?
One student considered:
1 square yard costs 18 pence.
Therefore 1 yard costs , or 4.243, pence.
Therefore 1 foot costs 4.243 ÷ 3 = 1.414 pence.
Therefore 1 square foot costs 1.4142 = 2 pence.
(Via Eureka.)
05/26/2026 UPDATE: Reader Catalin Voinescu adds:
For more dimensional fun, check out ‘ohms per square’ (symbol: capital omega divided by a literal square). The resistance of sheet material depends only on the shape of the object, not on the scale (assuming the thickness of the sheet stays the same). Any square of a given material, of any size, has the same resistance when measured between opposite edges. Longer, narrower shapes have higher resistance, and shorter, wider ones have lower resistance, but only the aspect ratio matters, not the actual dimensions. So the resistivity of conductive sheet is expressed as the resistance of a square piece of that material: ohms per square. This unit is used in electrical engineering, where thin conductive layers and foils are common, most obviously in PCB manufacturing, but also in the manufacturing of resistors, capacitors, semiconductors, batteries and solar panels.
(Thanks, Catalin.)




