The rupee today surged by a whopping 64 paise against the US dollar, the biggest one-day gain in nearly 12 months. This follows heavy selling of the American currency amid its loss against euro.Euro climbed against the dollar after EU and IMF unveiled a combined 1 trillion dollar rescue package to save the euro zone currency.Banks and exporters sold dollar heavily following weakness in the US currency overseas and expectations of more fall in the near term.In fairly active trade at the Interbank Foreign Exchange market, the local unit closed at 44 rupees 84 paise a dollar, a gain of 1.41 per cent, or 64 paise.