Another one of our easy to state, but difficult to solve puzzles - we do like them!
All you have to do is find a 4-digit number where the first digit is the number of zeroes in the number, the second digit is the number of ones, the third is the number of twos, and the fourth is the number of threes.
There are two of them to find.
And if you've found them, you can keep going and find a 5-digit number where the first digit is the number of zeroes, etc.
There are also one 7-digit number, one 8-digit number, one 9-digit number and one 10-digit number that you can find.
The numbers you are looking for are
1,210 and 2,020
21,200
3,211,000
42,101,000
521,001,000
and 6,210001,000