how big is the black hole?

Question: how big is the black hole?
- Keywords:
  black hole,
  Life Science Centre,
  space
Asked by anon-271254 to Hayley on 2 Dec 2020.
- Hayley and the Mars Rover answered on 2 Dec 2020:
  
  Black holes can be tens of billions of miles across! You can get supermassive and ultramassive black holes!

Question: how big is the black hole?