Question

How many different positive integers can be expressed in k digits using radix r numbers?

Answer 1

Let us take an example with radix 10, using 2 digits we can write from 0,1,23....95,96,97,98 and 99 that is total 100=
`10^(2)` numbers

Similarly using 3 digits, we can write from 0 to 999= 1000 =
`10^(3)` numbers.

Generalizing this we can express
`r^(k)` numbers using k-digits in a radix r.