How many 3-digit natural numbers are there?

900

Step-by-step explanation:

The 3-digit natural numbers are all whole numbers from 100 to 999.

There are 999 whole numbers from 1 to 999.

Since from 1 to 99 they are 2-digit numbers, and there are 99 of them, you need to subtract 99 numbers from 999 numbers.

999 - 99 = 900

Answer: 900