If you are up with the play on hexadecimal base numbers like the boys at John McGlashan College, the next three numbers in the series are "pretty straightforward".
It was one of many challenging questions for young mathematicians competing in the NumberWorks'nWords O'MAthalon Otago secondary schools senior mathematics competition at the Dunedin City Library this week.
Pupils from the college won the year 11, 12 and 13 levels of the competition, the first time the achievement had been recorded, mathematics head Ainslie Anderson said.
"This is unprecedented. I can't believe it. To have won all three sections is fantastic.
"They are very good mathematicians, but they are also very competitive," she said.
"Some of these boys will be running the country in some shape or form in 10 years' time."
Year 13 pupil Jamie Parkinson-Wisely (17) said he and his team-mates were proud of their achievement.
Despite the challenging nature of the questions, they appeared confident when asked what the answer was to the "hexadecimal base" question.
"312211, 13112221, 1113213211," was rattled off without fuss.
The competition will continue next Wednesday when year 5-10 pupils do battle at the Edgar Centre, in Dunedin.
Results were: Year 11: John McGlashan College (1), Otago Girls' High School (2), St Hilda's Collegiate School (3). Year 12: John McGlashan College (1), Taieri College and Kaikorai Valley College (equal 2). Year 13: John McGlashan College (1), Columba College (2), Logan Park High School (3).
