Nikolaj misreads the signs
Here's a brief description of the contestant's attempt. Someone's probably working writing up more detail!
Nikolaj mistakenly reads the multiplication sign on the task brief as a plus sign. When given the choice, in studio, of which sign should be used in the calculation for his score, he chooses multiplication and scores 136 points, winning the task. Presumably, if he'd chosen addition, his score would have been even lower, but he would have won either way.
(Written by Karl Craven)