Arithmetic on today's supply, not a forecast. It assumes nothing about whether Zcash could attract that much money.
A coin's market capitalisation is its price multiplied by the number of coins in circulation. Zcash has 16,903,674 ZEC in circulation at $1,141.10 each, which is $19.29B. Holding that supply still and putting Dogecoin's $14.53B in its place gives $859.8427 per ZEC.
Zcash is already worth more than Dogecoin. Moving to the smaller cap would take ZEC down to $859.8427, which is 0.754x of what it trades at now.
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 ZEC at that level, which is the part that actually decides a price.
$859.8427 per ZEC. That is Dogecoin's current market capitalisation of $14.53B divided across the 16,903,674 ZEC in circulation.
0.754x. Zcash trades at $1,141.10 today and Dogecoin's market cap is $14.53B against Zcash's $19.29B.
No. It is one division: Dogecoin's market capitalisation spread over the supply of ZEC that exists today. It assumes nothing about whether Zcash 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 $14.53B of market cap spread over more coins gives a lower price per coin. This uses the 16,903,674 ZEC in circulation now.