| 2025-12-01 | ___ 1 (speed of sound) |
| 2025-06-27 | Scientist whose "number" is a dimensionless ratio |
| 2025-01-06 | Supersonic speed number |
| 2024-09-20 | Kind of number represented by the equation M = v/c |
| 2023-12-25 | Physicist Ernst |
| 2023-06-22 | Name associated with speed |
| 2023-03-29 | Ernst who studied sonic booms |
| 2022-01-22 | Speed of sound |
| 2021-08-27 | It's calculated relative to the speed of sound |
| 2020-02-20 | Speed measure |
| 2019-05-16 | South American landmark whose name means "old peak" |
| 2019-03-13 | Eponymous physicist Ernst |
| 2017-01-20 | Eponymous physicist Ernst |
| 2015-09-16 | Speed-of-sound ratio |
| 2013-08-07 | See 13-Down |
| 2012-03-16 | Physicist Ernst who studied shock waves |
| 2010-11-21 | Name often followed by a number |
| 2007-03-07 | Supersonic unit |
| 2006-03-22 | Word often followed by a numeral |
| 2006-02-04 | Number associated with a boom |
| 2003-05-02 | Physicist with an eponymous number |
| 2001-09-17 | Jet speed unit |
| 2000-11-01 | ___ one |
| 1999-07-20 | Speed-of-sound number |
| 1998-11-17 | Jet speed measure |
| 1998-09-23 | Flight ratio |
| 1998-05-20 | Speed ratio |
| 1997-11-15 | Word before 1 or 2 |
| 1996-02-19 | Airspeed unit |
| 1995-10-17 | High-speed number |
| 1995-09-19 | Supersonic number |
| 1995-04-23 | Kind of number |
| 1994-09-18 | Physicist Ernst |