Arithmetic on today's supply, not a forecast. It assumes nothing about whether BNB could attract that much money.
A coin's market capitalisation is its price multiplied by the number of coins in circulation. BNB has 133,032,284 BNB in circulation at $726.9600 each, which is $96.71B. Holding that supply still and putting XRP's $85.78B in its place gives $644.7692 per BNB.
BNB is already worth more than XRP. Moving to the smaller cap would take BNB down to $644.7692, which is 0.887x 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 BNB at that level, which is the part that actually decides a price.
$644.7692 per BNB. That is XRP's current market capitalisation of $85.78B divided across the 133,032,284 BNB in circulation.
0.887x. BNB trades at $726.9600 today and XRP's market cap is $85.78B against BNB's $96.71B.
No. It is one division: XRP's market capitalisation spread over the supply of BNB that exists today. It assumes nothing about whether BNB 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 $85.78B of market cap spread over more coins gives a lower price per coin. This uses the 133,032,284 BNB in circulation now.