How do we calculate the airdrop amount?

Luna original “TOTAL SUPPLY” before depeg was 1B. “CIRCULATING SUPPLY” was ~342M as 7th May.

Divide current total supply of 6.9T by 1B = ~6,900.

Divide your Luna post depeg holding by 6,900 to get the valuation of your Luna back dated to 7th may.
Example: 1,000,000 Luna post depeg divided by 6,900 (1,000,000÷6,900) =
144.93 pre depeg.

So depending at what price you purchased post depeg you will get 144.93 Luna2.

Assuming Luna2 is listed at 7th May’s price of ~$75, you should get 144.93 ×(~$75)
=$10,869.75