what four digits do not appear in the first twenty square numbers?
Maybe 242 ???? → 576
1,4,9,16,25,36,49,64,81,100
121,144,169,196,225,256,289,324,361,400
There is the first 20 squared numbers
7 is the only digit not there.
Now the question becomes.
Does any squared number contain the digit 7 ?
If so what is the first squared number that contains the digit 7 ?