A father in his will left all his money to his children in the following manner:

$1000 to the first born and 1/10 of what then remains,

then $2000 to the second born and 1/10 of what remains,

then $3000 to the third born and 1/10 of what then remains, and so on.

When this was done each child had the same amount. How many children were there?

Which way is fastest and easiest? :/