She said the Year 8 Whanganui Intermediate team managed a clean sweep.
"That is something no one remembers having ever happened before," she said.
Fordell School came first in Year 5 and Year 7 and Mosston School was first in Year 6.
Fordell principal Yvette Moorhouse said the teams "absolutely love everything maths" and Year 7 team members have been winning their year level at Mathex for the past four years.
These were the final placings:
Year 5: 1st Fordell (Angus Pearce, Sam Cranstone, Lennox Brotherton, Max McGregor) 20 correct in a time of 18 minutes 30 seconds; 2nd Hunterville (Iris Collie, Harry McVerry, Zach Nydegger-Monks, Sam Livingston); 3rd Bulls (Sophie Coote, Toby Smith, Jordan Tamati, Aden Simons).
Year 6: 1st Mosston (Matthew Leith, Philip Dale, Coby Chambers, Glen Mallett) 20 correct in a time of 27 minutes 47 seconds; 2nd St Johns Hill (Sophia Bedwell, Hannah Palmer, Antonia Harding, Jurek Sosnowski); 3rd Westmere (Alyssa Hartley, Samuel Greaves, Mac Lawrence, Alex Sturzaker).
Year 7: 1st Fordell (Lauren Phillips, Michael O'Neill, Elena O'Leary, John Bryant) 20 correct in a time of 18 minutes 14 seconds; 2nd Wanganui Intermediate (Calum Sinclair, Firooze Coolabavala, Maddi McKenzie, Amy Bennetts); 3rd St Georges (Amy Maskery, Daniel Burgess, Benjamin White, Molly Davis)
Year 8: 1st Wanganui Intermediate (Caleb Jackson, Kera Forrest, Tainn Simpson, Troy Brennan) 20 correct in a time of 24 minutes 46 seconds; 2nd Wanganui Intermediate (Jeffrey Lin, Will Southee, Flynn Johnston, Mia Perkins); 3rd Wanganui Intermediate (Tayla Robbertsen, Grace Gould, Rose Wildin, Jada Hoekstra).