Arithmetic on today's supply, not a forecast. It assumes nothing about whether Polkadot could attract that much money.
A coin's market capitalisation is its price multiplied by the number of coins in circulation. Polkadot has 1,700,506,167 DOT in circulation at $1.0190 each, which is $1.73B. Holding that supply still and putting Zcash's $19.26B in its place gives $11.3263 per DOT.
Polkadot would have to take on $17.53B of new money to get there. A 11.1x move is large: it happens, and it usually needs the whole market to grow instead of one coin to take share from another.
Supply is held still, and in practice it moves: coins are minted, burned and unlocked, and every one of those changes the price a given market capitalisation implies. The figure also says nothing about whether the money exists to buy DOT at that level, which is the part that actually decides a price.
$11.3263 per DOT. That is Zcash's current market capitalisation of $19.26B divided across the 1,700,506,167 DOT in circulation.
11.1x. Polkadot trades at $1.0190 today and Zcash's market cap is $19.26B against Polkadot's $1.73B.
No. It is one division: Zcash's market capitalisation spread over the supply of DOT that exists today. It assumes nothing about whether Polkadot could attract that much money, and it holds the supply still when in practice supply changes.
It sets it. Market cap is price times circulating supply, so the same $19.26B of market cap spread over more coins gives a lower price per coin. This uses the 1,700,506,167 DOT in circulation now.