1,2,3,5,7,9,11,13,17,19
The square numbers between 1 and 20 are 1,4,9 and 16.
All whole numbers between 1 and 400 (=20 square).
There are 167960 9 digits combinations between numbers 1 and 20.
There are (not counting 1) three square numbers between 1 and 20.
There are 8 prime numbers between 1 and 20. The numbers are 2, 3, 5, 7, 11, 13, 17, and 19.
1, 2, 4, 5, 10, 20
20 of them.
There are eleven of them including 20
There are 31 perfect square numbers between 1 and 1000 (including 1).
Just 6
1
20