31. Natural numbers greater than 1000 composed of the digits $0,1,2$ (which can be used entirely or partially), arranged in ascending order, what is the position of 2010?
31. The natural numbers greater than 1000 composed of the digits $0,1,2$ (which can be used entirely or partially), arranged in ascending order, what is the position of 2010?
【Analysis】The natural numbers greater than 1000 composed of the digits $0,1,2$ (which can be used entirely or partially), arranged in ascending order, have 26 numbers starting with 1, which is $3 \times 3 \times 3-1=26$. The smallest number starting with 2 is 2000, followed by 2001, 2002, and 2010, from which the conclusion can be drawn.
【Solution】Solution: The natural numbers greater than 1000 composed of the digits $0,1,2$ (which can be used entirely or partially), arranged in ascending order,
starting with 1, there are $3 \times 3 \times 3-1=26$ numbers,
starting with 2, the smallest is 2000, followed by 2001, 2002, and 2010.
Therefore, 2010 is the $26+4=30$ (th).
Answer: 2010 is in the 30th position.