7
meadowood
89,999 different numbers i guess
There are many different standard forms: standard forms of numbers, of linear equations, of circles, etc. The standard form of numbers simplifies working with very large and very small numbers.
5
There are many different systems of using numbers to represent letters. Binary is commonly used.
1000
216 different codes
24
The four digits can be used to produce infinitely many different numbers if repetition is permitted. Without repetition, there are 24 possible numbers. A lot more can be produced if the numbers are combined using binary oprations, fore example, 19 * 8/4 = 19*2 = 38.
With base one million, you can create one nonillion different numbers; using the traditional decimal (base ten) system, you can form 100 thousand different numbers.
15
10,000
575757