Ans. Given the sheer economic size of the USA, the US Dollar is the strongest currency in the world. As per an IMF report, About 61% of the total foreign exchange reserves of all of the known Central Banks in the world were held only in US dollar which makes USD the most popular and trusted currency of the world. Though you may find currencies such as Euro and British Pounds more expensive than US dollar but that is only in the nominal currency exchange terms which do not reflect relative economic strengths of respective countries.