In any system of counting, there are exactly the same number of digits as the base. They go from 0 to one less than the base.
There are many more than ten bases. If this question is part of a homework assignment, you'll need to actually read it yourself to determine what specific ten bases were mentioned in the text. Some...
The binary representation of the decimal number 77 is 1001101.
aerchaebacteria is a type of bacteria
decimal