Number representation in python

Question

https://code.sololearn.com/cluLI1bR8Qt1/?ref=app
Please look into the code and explain why 3rd line is throwing Error.

Answer 1

I understand that putting 0b will make it binary number. similar changes will take place with 0o and 0x. but what I want to know that why my code doesn't work the way I want ? Why explicit declaration is needed ?

Answer 2

Okay. So Can I conclude that this is the rule and there is no logic behind it ?