SortStack #781 — 2028-07-29

By duration · Order from shortest to longest.

1. One full revolution of a helicopter's main rotor 150 ms

   Main rotors spin at only a few hundred rpm, but the blade tips travel so fast they approach the speed of sound — the source of that thudding chop.

2. A proper hand wash, by WHO guidelines 19.8 sec

   The recommended scrub lasts about as long as singing 'Happy Birthday' twice — most people manage barely a third of it.

3. An average swim across the English Channel 13.5 h

   Fewer people have swum the Channel than have climbed Everest — and rules forbid wetsuits, allowing only goggles, a cap, and grease.

4. Holi, the Hindu festival of colours 2 days

   It opens with the Holika bonfire at night and erupts into colour-throwing the next day — the powders were traditionally made from flowers and herbs.

5. The Second World War 6 years

   From the invasion of Poland to Japan's surrender, it remains history's deadliest conflict — fighting officially ended on a battleship in Tokyo Bay.

6. How long Jericho has been continuously inhabited 10.8K years

   Among the world's oldest cities, Jericho's stone tower predates pottery itself — people built monuments before they made bowls.

← All puzzles · Play today’s SortStack