All natural numbers, starting from one, are written in ascending order: 1234567891011121314. What digit is in the hundredth place, and what digit is in the thousandth place?

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At the beginning, there are 9 single-digit numbers, followed by 90 two-digit numbers (180 digits).

1) $100-9=91$, so at the beginning, there are 9 single-digit numbers, then 45 two-digit numbers, and the first digit of the 46th number, which means the last digit is 4.
2) $1000-9-189=811=270 \times 3+1$, so at the beginning, there are 9 single-digit numbers, then 90 two-digit numbers, followed by 270 three-digit numbers, and then the first digit of the 271st number, which means the 1000th digit is 2.