NB! The deadline for Problem 3 is extended by one more week, until 11th April, 23:59GMT. Also, those contestants who’ll manage to get as far as missing only one correct frequency will be able to get an additional extension by two more days, for one final attempt .
By 28th March 2021, there are 1009 registered participants from 71 countries (the list of countries is given below). During the first four weeks, 48 solutions were submitted, out of which 14 were correct.
Correct solutions were submitted by:
| First Name | Surname | Country | School/University | date | time |
| Zhening | Li | Canada | Sir John A. Macdonald Secondary School | 28/02/21 | 20:37 |
| Huiyuan | Wang | China | University of Cambridge | 01/03/21 | 08:56 |
| Yuechen | Zhu | China | Peking University | 01/03/21 | 15:22 |
| Lotus | Chen | China | No.2 High School Shijiazhuang | 01/03/21 | 15:39 |
| Nikita | Semenin | Russia | Moscow Institute of Physics and Technology | 01/03/21 | 17:56 |
| Oliwier | Urbański | Poland | Liceum Ogólnokształcące nr 7 w Poznaniu | 02/03/21 | 14:11 |
| Eddie | Chen | United States | West-Windsor Plainsboro High School North | 06/03/21 | 02:05 |
| Qian | Lin | China | University of Oxford | 11/03/21 | 23:47 |
| Yanjun | Zhou | United Kingdom | University of Oxford | 16/03/21 | 06:26 |
| Antonia | Ghita | Romania | International Computer High School of Bucharest | 17/03/21 | 08:43 |
| Jie | Wang | China | Zhangjiakou No.1 Middle School | 24/03/21 | 03:11 |
| Ameya Vikrama | Singh | India | FIITJEE Junior College | 25/03/21 | 08:20 |
| Vuk | Hip | Serbia | Mathematical grammar school | 01/04/21 | 14:35 |
| Pieter | Van Steenweghen | Belgium | Imperial College London | 03/04/21 | 23:02 |
Participating countries: Algeria, Azerbaijan, Australia, Bangladesh, Belarus, Belgium, Bosnia and Herzegovina, Bolivia, Brazil, Bulgaria, Cambodia, Canada, China, Croatia, Czechia, Egypt, El Salvador, Estonia, Finland, Georgia, Germany, Greece, Hungary, India, Indonesia, Iran, Israel, Italy, Japan, Kazakhstan, Kenya, Korea, Kyrgyzstan, Latvia, Lebanon, Lithuania, Macedonia, Malaysia, Mexico, Moldova, Mongolia, Nepal, Nigeria, North Macedonia, Pakistan, Peru, Philippines, Poland, Romania, Russia, Saudi Arabia, Serbia, Singapore, Slovakia, Slovenia, South Africa, South Korea, Spain, Sri Lanka, Sweden, Switzerland, Syria, Taiwan, Thailand, Turkey, Turkmenistan, United Arab Emirates, United Kingdom, United States, Uzbekistan, Vietnam.