A binary (aka, digital) option can be either an asset-or-nothing binary or a cash-or-nothing. The asset-or-nothing call pays the full asset price if the stock price exceeds the strike price at maturity; the cash-or-nothing call pays a fixed cash amount, denoted "Q," if the stock price exceeds the strike price at maturity. The key to valuation is to realize that the asset-or-nothing is equivalent to (i.e., its payoff is equal to) the portfolio consisting of a standard option plus a cash-or-nothing (conditional on K = Q).
David's XLS: https://trtl.bz/2PqyFVk
David's XLS: https://trtl.bz/2PqyFVk
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