I’m thinking of a positive number, not necessarily an integer.

It’s between 0 and 1,000,000 (exclusive).

Every time the number of reasonable guesses increases ten-fold, I will reveal a digit of the number.

Since no posts have been made so far, I will start off by revealing that the number starts with a 4.

If the number is irrational, exact answers will be given more credit than decimal approximations (or truncated responses)

eg

sqrt(3) is given more credit that 1.732

(that is not the number)

If the number is rational, giving the actual fraction (simplified plz) will garner more credit.

eg

7/5 gets more credit than 14/10, which in turn gets more credit than 1.4

Whoever gets the most credit gets bragging rights.

The number is not something that one would think of right away.

The number will not change as the game progresses.

It has been written down, both in pencil and in notepad.