How many generations does it take for a single bacterial cell to become 256 bacterial cells? (hint, don't forget to count the first cell)?

Bacteria is a unicellular organism which can multiply very fast by binary cell division.
To get a number of divisions required for cell division: you can use the formula: 2 = number of bacteria
To get 256 bacteria:
2 = 256  (you can solve this equation by a calculator)
so:  n = 8 generations

With this formula the first bacteria is taken into consideration since 1 bacteria gives two, then the two give four, then eight, 16...