1. Variant 1.

Write the smallest number with a digit sum of 62, in the notation of which at least three different digits are used.
Answer: 17999999.

Solution: $62=9 \cdot 6+8$. That is, the number is at least a seven-digit number. But if it is a seven-digit number, then in its decimal representation there are exactly 6 nines and 1 eight. According to the problem, the number must contain at least three different digits, so it is at least an eight-digit number. The first digit is no less than 1, and the sum of the first and second digits is no less than 8. By splitting 8 into $1+7$, we get the answer 17999999.