Comparing and ordering numbers

Suppose you had to begin the never ending task of writing out the natural numbers: 1, 2, 3, 4, 5.... and so on. What would be the 1000th digit you would write down.

There are lots of ideas to explore in these sequences of ordered fractions.

Use the differences to find the solution to this Sudoku.

Which is the bigger, 9^10 or 10^9 ? Which is the bigger, 99^100 or 100^99 ?