A single currency for a global economy. The daily turnover in the foreign exchange market approaches $4 trillion or a yearly turnover of $1,000 trillion

(with 252 working days in a given year). Assuming a bid-ask spread of 5 basis points (the difference at which currencies are bought or sold), what would be the annual savings of abolishing national currencies? What would be the costs of doing away with national currencies? Would you advocate a single world currency for an increasingly globalized world economy?