Since one-third of the class participated, there are 39 * 1/3 = <<39*1/3=13>>13 students who participated in the competition.

This means that 39 – 13 = <<39-13=26>>26 students did not participate.

# Answer

26
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
One-third of a class of 39 students took part in a math competition. How many students did not participate in the competition?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
26
One-third of a class of 39 students took part in a math competition. How many students did not participate in the competition?
train