`10 + max(0, 10 - r + if(r = 1, 1)) * n`

r is rank

n is number of players in the tournament

if(r = 1, 1) will yield 1 point if the player is ranked 1st, 0 otherwise

10 - r + if(r = 1, 1) gives the 1, 2, 3, ..., to 10 for the players ranked 9th through 1st. For players ranked 10th or higher, the result will be a negative number. The max(0, ...) makes sure any negative numbers are turned into zero.

Then multiply by number of players and add 10.