$query = array( 'author' => 'admin', 'post' => array( array( 'title' => '1', 'body' => '1' ) ) )
If you compare a number with a string or the comparison involves numerical strings, then each string is converted to a number and the comparison performed numerically.
The value is given by the initial portion of the string. If the string starts with valid numeric data, this will be the value used. Otherwise, the value will be 0 (zero).